diff --git a/.gitignore b/.gitignore
index c9e2809..4a7fec5 100755
--- a/.gitignore
+++ b/.gitignore
@@ -5,3 +5,4 @@ __pycache__
 error_*
 *.log
 /logs/
+.vscode
\ No newline at end of file
diff --git a/README.md b/README.md
index a3d936b..ec9ff4f 100644
--- a/README.md
+++ b/README.md
@@ -43,7 +43,10 @@
 * %react - rank users by their reactions
   * arguments:
     * <n> - top <n> messages, default is 10
-* %cancel - cancel current analysis
+* %words - rank words by their usage
+  * arguments:
+    * <n> - top <n> words, default is 10
+* %cancel - cancel current analysis (not launched with fast)
 
 * Common arguments:
     * @member/me: filter for one or more member
@@ -100,8 +103,12 @@ python3 src/main.py
 
 ## Changelog
 
+* **v1.12**
+  * more scans: `%words`
+  * concurrent `fast` analysis
+  * assume `fast` if last analysis is fresh
 * **v1.11**
-  * more scans `%first`, `%rand`, `%last`
+  * more scans: `%first`, `%rand`, `%last`
   * streak computing in `%pres`
 * **v1.10**
   * multithreading for queries
diff --git a/src/logs/channel_logs.py b/src/logs/channel_logs.py
index 65290a0..86c7a28 100644
--- a/src/logs/channel_logs.py
+++ b/src/logs/channel_logs.py
@@ -40,7 +40,12 @@ class ChannelLogs:
         self.channel = channel
         try:
             if self.last_message_id is not None:  # append
-                while self.last_message_id != channel.last_message_id:
+                tmp_message_id = None
+                while (
+                    self.last_message_id != channel.last_message_id
+                    and self.last_message_id != tmp_message_id
+                ):
+                    tmp_message_id = self.last_message_id
                     async for message in channel.history(
                         limit=CHUNK_SIZE,
                         after=FakeMessage(self.last_message_id),
diff --git a/src/logs/guild_logs.py b/src/logs/guild_logs.py
index 7f3cecb..88d8823 100644
--- a/src/logs/guild_logs.py
+++ b/src/logs/guild_logs.py
@@ -4,6 +4,7 @@ import discord
 import json
 import gzip
 from datetime import datetime
+import time
 import logging
 import asyncio
 import threading
@@ -22,6 +23,8 @@ current_analysis_lock = threading.Lock()
 ALREADY_RUNNING = -100
 CANCELLED = -200
 
+MIN_MODIFICATION_TIME = 5 * 60
+
 
 class Worker:
     def __init__(self, channel_log: ChannelLogs, channel: discord.TextChannel):
@@ -53,12 +56,39 @@ class GuildLogs:
         self.guild = guild
         self.log_file = os.path.join(LOG_DIR, f"{guild.id}.logz")
         self.channels = {}
+        self.locked = False
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, type, value, tb):
+        del self.channels
+        del self.guild
+        if self.locked:
+            self.unlock()
 
     def dict(self) -> dict:
         return {id: self.channels[id].dict() for id in self.channels}
 
     def check_cancelled(self) -> bool:
-        return self.log_file not in current_analysis
+        return self.locked and self.log_file not in current_analysis
+
+    def lock(self) -> bool:
+        self.locked = True
+        current_analysis_lock.acquire()
+        if self.log_file in current_analysis:
+            current_analysis_lock.release()
+            return False
+        current_analysis.append(self.log_file)
+        current_analysis_lock.release()
+        return True
+
+    def unlock(self):
+        self.locked = False
+        current_analysis_lock.acquire()
+        if self.log_file in current_analysis:
+            current_analysis.remove(self.log_file)
+        current_analysis_lock.release()
 
     async def load(
         self,
@@ -68,19 +98,18 @@ class GuildLogs:
         fast: bool,
         fresh: bool,
     ) -> Tuple[int, int]:
-        current_analysis_lock.acquire()
-        if self.log_file in current_analysis:
-            current_analysis_lock.release()
+        self.locked = False
+        if not fast and not self.lock():
             return ALREADY_RUNNING, 0
-        current_analysis.append(self.log_file)
-        current_analysis_lock.release()
         t00 = datetime.now()
         # read logs
         if not os.path.exists(LOG_DIR):
             os.mkdir(LOG_DIR)
+        last_time = None
         if os.path.exists(self.log_file):
             channels = {}
             try:
+                last_time = os.path.getmtime(self.log_file)
                 gziped_data = None
                 await code_message(progress, "Reading saved history (1/4)...")
                 t0 = datetime.now()
@@ -92,6 +121,7 @@ class GuildLogs:
                 await code_message(progress, "Reading saved history (2/4)...")
                 t0 = datetime.now()
                 json_data = gzip.decompress(gziped_data)
+                del gziped_data
                 logging.info(
                     f"log {self.guild.id} > gzip decompress in {delta(t0):,}ms"
                 )
@@ -100,6 +130,7 @@ class GuildLogs:
                 await code_message(progress, "Reading saved history (3/4)...")
                 t0 = datetime.now()
                 channels = json.loads(json_data)
+                del json_data
                 logging.info(f"log {self.guild.id} > json parse in {delta(t0):,}ms")
                 if self.check_cancelled():
                     return CANCELLED, 0
@@ -122,31 +153,54 @@ class GuildLogs:
         else:
             fast = False
 
+        if len(target_channels) == 0:
+            target_channels = (
+                self.channels.values() if fast else self.guild.text_channels
+            )
+        elif fast:
+            # select already loaded channels only
+            target_channels_tmp = [
+                channel for channel in target_channels if channel.id in self.channels
+            ]
+            if len(target_channels_tmp) == 0:
+                fast = False
+            else:
+                target_channels = target_channels_tmp
+
+        # assume fast if file is fresh
+        if (
+            not fast
+            and not fresh
+            and last_time is not None
+            and (time.time() - last_time) < MIN_MODIFICATION_TIME
+        ):
+            invalid_target_channels = [
+                channel
+                for channel in target_channels
+                if channel.id not in self.channels
+            ]
+            if len(invalid_target_channels) == 0:
+                fast = True
+                if self.locked:
+                    self.unlock()
+
         total_msg = 0
         total_chan = 0
         if fast:
-            if len(target_channels) == 0:
-                total_msg = sum(
-                    [len(channel.messages) for channel in self.channels.values()]
-                )
-                total_chan = len(self.channels)
-            else:
-                target_channels_id = [channel.id for channel in target_channels]
-                total_msg = sum(
-                    [
-                        len(channel.messages)
-                        for channel in self.channels.values()
-                        if channel.id in target_channels_id
-                    ]
-                )
-                total_chan = len(target_channels)
+            target_channels_id = [channel.id for channel in target_channels]
+            total_msg = sum(
+                [
+                    len(channel.messages)
+                    for channel in self.channels.values()
+                    if channel.id in target_channels_id
+                ]
+            )
+            total_chan = len(target_channels)
         else:
+            if not self.locked and not self.lock():
+                return ALREADY_RUNNING, 0
             # load channels
             t0 = datetime.now()
-            if len(target_channels) == 0:
-                target_channels = (
-                    self.guild.text_channels if not fast else self.channels.keys()
-                )
             loading_new = 0
             queried_msg = 0
             total_chan = 0
@@ -225,6 +279,7 @@ class GuildLogs:
             )
             t0 = datetime.now()
             gziped_data = gzip.compress(json_data)
+            del json_data
             logging.info(
                 f"log {self.guild.id} > gzip in {delta(t0):,}ms -> {real_total_msg / deltas(t0):,.3f} m/s"
             )
@@ -237,6 +292,7 @@ class GuildLogs:
             t0 = datetime.now()
             with open(self.log_file, mode="wb") as f:
                 f.write(gziped_data)
+            del gziped_data
             logging.info(
                 f"log {self.guild.id} > saved in {delta(t0):,}ms -> {real_total_msg / deltas(t0):,.3f} m/s"
             )
@@ -247,9 +303,10 @@ class GuildLogs:
             f"Analysing...\n{total_msg:,} messages in {total_chan:,} channels",
         )
         logging.info(f"log {self.guild.id} > TOTAL TIME: {delta(t00):,}ms")
-        current_analysis_lock.acquire()
-        current_analysis.remove(self.log_file)
-        current_analysis_lock.release()
+        if self.locked:
+            current_analysis_lock.acquire()
+            current_analysis.remove(self.log_file)
+            current_analysis_lock.release()
         return total_msg, total_chan
 
     @staticmethod
@@ -262,5 +319,6 @@ class GuildLogs:
         else:
             current_analysis_lock.release()
             await message.channel.send(
-                f"No analysis are currently running on this server", reference=message
+                f"No cancellable analysis are currently running on this server",
+                reference=message,
             )
diff --git a/src/main.py b/src/main.py
index 2f73357..565e92d 100644
--- a/src/main.py
+++ b/src/main.py
@@ -21,6 +21,7 @@ from scanners import (
     FirstScanner,
     RandomScanner,
     LastScanner,
+    WordsScanner,
 )
 from logs import GuildLogs
 
@@ -32,7 +33,7 @@ emojis.load_emojis()
 
 bot = Bot(
     "Discord Analyst",
-    "1.11",
+    "1.12",
     alias="%",
 )
 
@@ -41,8 +42,8 @@ bot.log_calls = True
 bot.register_command(
     "(cancel|stop)",
     GuildLogs.cancel,
-    "cancel: stop current analysis",
-    "```\n" + "%cancel: Stop current analysis\n" + "```",
+    "cancel: stop current analysis (not launched with fast)",
+    "```\n" + "%cancel: Stop current analysis (not launched with fast)\n" + "```",
 )
 bot.register_command(
     "last",
@@ -62,6 +63,12 @@ bot.register_command(
     "first: read first message",
     FirstScanner.help(),
 )
+bot.register_command(
+    "words",
+    lambda *args: WordsScanner().compute(*args),
+    "words: rank words by their usage",
+    WordsScanner.help(),
+)
 bot.register_command(
     "mentioned",
     lambda *args: MentionedScanner().compute(*args),
diff --git a/src/scanners/__init__.py b/src/scanners/__init__.py
index 37eaa77..21fd922 100644
--- a/src/scanners/__init__.py
+++ b/src/scanners/__init__.py
@@ -10,4 +10,5 @@ from .channels_scanner import ChannelsScanner
 from .reactions_scanner import ReactionsScanner
 from .first_scanner import FirstScanner
 from .last_scanner import LastScanner
-from .random_scanner import RandomScanner
\ No newline at end of file
+from .random_scanner import RandomScanner
+from .words_scanner import WordsScanner
\ No newline at end of file
diff --git a/src/scanners/scanner.py b/src/scanners/scanner.py
index 4a3b749..9a7e712 100644
--- a/src/scanners/scanner.py
+++ b/src/scanners/scanner.py
@@ -36,133 +36,134 @@ class Scanner(ABC):
     ):
         args = list(args)
         guild = message.guild
-        logs = GuildLogs(guild)
-
-        # If "%cmd help" redirect to "%help cmd"
-        if "help" in args:
-            await client.bot.help(client, message, "help", args[0])
-            return
-
-        # check args validity
-        str_channel_mentions = [str(channel.id) for channel in message.channel_mentions]
-        str_mentions = [str(member.id) for member in message.mentions]
-        for i, arg in enumerate(args[1:]):
-            if re.match(r"^<@!?\d+>$", arg):
-                arg = arg[3:-1] if "!" in arg else arg[2:-1]
-            elif re.match(r"^<#!?\d+>$", arg):
-                arg = arg[3:-1] if "!" in arg else arg[2:-1]
-            if (
-                arg not in self.valid_args + ["me", "here", "fast", "fresh"]
-                and (not arg.isdigit() or not self.has_digit_args)
-                and arg not in str_channel_mentions
-                and arg not in str_mentions
-            ):
-                await message.channel.send(
-                    f"Unrecognized argument: `{arg}`", reference=message
-                )
+        with GuildLogs(guild) as logs:
+            # If "%cmd help" redirect to "%help cmd"
+            if "help" in args:
+                await client.bot.help(client, message, "help", args[0])
                 return
 
-        # Get selected channels or all of them if no channel arguments
-        self.channels = no_duplicate(message.channel_mentions)
-
-        # transform the "here" arg
-        if "here" in args:
-            self.channels += [message.channel]
-
-        self.full = len(self.channels) == 0
-        if self.full:
-            self.channels = guild.text_channels
-
-        # Get selected members
-        self.members = no_duplicate(message.mentions)
-        self.raw_members = no_duplicate(message.raw_mentions)
-
-        # transform the "me" arg
-        if "me" in args:
-            self.members += [message.author]
-            self.raw_members += [message.author.id]
-
-        if not await self.init(message, *args):
-            return
-
-        # Start computing data
-        async with message.channel.typing():
-            progress = await message.channel.send(
-                "```Starting analysis...```",
-                reference=message,
-                allowed_mentions=discord.AllowedMentions.none(),
-            )
-            total_msg, total_chan = await logs.load(
-                progress, self.channels, fast="fast" in args, fresh="fresh" in args
-            )
-            if total_msg == CANCELLED:
-                await message.channel.send(
-                    "Operation cancelled by user",
-                    reference=message,
-                )
-            elif total_msg == ALREADY_RUNNING:
-                await message.channel.send(
-                    "An analysis is already running on this server, please be patient.",
-                    reference=message,
-                )
-            else:
-                self.msg_count = 0
-                self.total_msg = 0
-                self.chan_count = 0
-                t0 = datetime.now()
-                for channel in self.channels:
-                    if channel.id in logs.channels:
-                        channel_logs = logs.channels[channel.id]
-                        count = sum(
-                            [
-                                self.compute_message(channel_logs, message_log)
-                                for message_log in channel_logs.messages
-                            ]
-                        )
-                        self.total_msg += len(channel_logs.messages)
-                        self.msg_count += count
-                        self.chan_count += 1 if count > 0 else 0
-                logging.info(f"scan {guild.id} > scanned in {delta(t0):,}ms")
-                if self.total_msg == 0:
+            # check args validity
+            str_channel_mentions = [
+                str(channel.id) for channel in message.channel_mentions
+            ]
+            str_mentions = [str(member.id) for member in message.mentions]
+            for i, arg in enumerate(args[1:]):
+                if re.match(r"^<@!?\d+>$", arg):
+                    arg = arg[3:-1] if "!" in arg else arg[2:-1]
+                elif re.match(r"^<#!?\d+>$", arg):
+                    arg = arg[3:-1] if "!" in arg else arg[2:-1]
+                if (
+                    arg not in self.valid_args + ["me", "here", "fast", "fresh"]
+                    and (not arg.isdigit() or not self.has_digit_args)
+                    and arg not in str_channel_mentions
+                    and arg not in str_mentions
+                ):
                     await message.channel.send(
-                        "There are no messages found matching the filters",
+                        f"Unrecognized argument: `{arg}`", reference=message
+                    )
+                    return
+
+            # Get selected channels or all of them if no channel arguments
+            self.channels = no_duplicate(message.channel_mentions)
+
+            # transform the "here" arg
+            if "here" in args:
+                self.channels += [message.channel]
+
+            self.full = len(self.channels) == 0
+            if self.full:
+                self.channels = guild.text_channels
+
+            # Get selected members
+            self.members = no_duplicate(message.mentions)
+            self.raw_members = no_duplicate(message.raw_mentions)
+
+            # transform the "me" arg
+            if "me" in args:
+                self.members += [message.author]
+                self.raw_members += [message.author.id]
+
+            if not await self.init(message, *args):
+                return
+
+            # Start computing data
+            async with message.channel.typing():
+                progress = await message.channel.send(
+                    "```Starting analysis...```",
+                    reference=message,
+                    allowed_mentions=discord.AllowedMentions.none(),
+                )
+                total_msg, total_chan = await logs.load(
+                    progress, self.channels, fast="fast" in args, fresh="fresh" in args
+                )
+                if total_msg == CANCELLED:
+                    await message.channel.send(
+                        "Operation cancelled by user",
+                        reference=message,
+                    )
+                elif total_msg == ALREADY_RUNNING:
+                    await message.channel.send(
+                        "An analysis is already running on this server, please be patient.",
                         reference=message,
                     )
                 else:
-                    await progress.edit(content="```Computing results...```")
-                    # Display results
+                    self.msg_count = 0
+                    self.total_msg = 0
+                    self.chan_count = 0
                     t0 = datetime.now()
-                    results = self.get_results(
-                        get_intro(
-                            self.intro_context,
-                            self.full,
-                            self.channels,
-                            self.members,
-                            self.msg_count,
-                            self.chan_count,
+                    for channel in self.channels:
+                        if channel.id in logs.channels:
+                            channel_logs = logs.channels[channel.id]
+                            count = sum(
+                                [
+                                    self.compute_message(channel_logs, message_log)
+                                    for message_log in channel_logs.messages
+                                ]
+                            )
+                            self.total_msg += len(channel_logs.messages)
+                            self.msg_count += count
+                            self.chan_count += 1 if count > 0 else 0
+                    logging.info(f"scan {guild.id} > scanned in {delta(t0):,}ms")
+                    if self.total_msg == 0:
+                        await message.channel.send(
+                            "There are no messages found matching the filters",
+                            reference=message,
                         )
-                    )
-                    logging.info(f"scan {guild.id} > results in {delta(t0):,}ms")
-                    response = ""
-                    first = True
-                    for r in results:
-                        if len(response + "\n" + r) > 2000:
+                    else:
+                        await progress.edit(content="```Computing results...```")
+                        # Display results
+                        t0 = datetime.now()
+                        results = self.get_results(
+                            get_intro(
+                                self.intro_context,
+                                self.full,
+                                self.channels,
+                                self.members,
+                                self.msg_count,
+                                self.chan_count,
+                            )
+                        )
+                        logging.info(f"scan {guild.id} > results in {delta(t0):,}ms")
+                        response = ""
+                        first = True
+                        for r in results:
+                            if len(response + "\n" + r) > 2000:
+                                await message.channel.send(
+                                    response,
+                                    reference=message if first else None,
+                                    allowed_mentions=discord.AllowedMentions.none(),
+                                )
+                                first = False
+                                response = ""
+                            response += "\n" + r
+                        if len(response) > 0:
                             await message.channel.send(
                                 response,
                                 reference=message if first else None,
                                 allowed_mentions=discord.AllowedMentions.none(),
                             )
-                            first = False
-                            response = ""
-                        response += "\n" + r
-                    if len(response) > 0:
-                        await message.channel.send(
-                            response,
-                            reference=message if first else None,
-                            allowed_mentions=discord.AllowedMentions.none(),
-                        )
-            # Delete custom progress message
-            await progress.delete()
+                # Delete custom progress message
+                await progress.delete()
 
     @abstractmethod
     async def init(self, message: discord.Message, *args: str) -> bool:
diff --git a/src/scanners/words_scanner.py b/src/scanners/words_scanner.py
new file mode 100644
index 0000000..cae33bf
--- /dev/null
+++ b/src/scanners/words_scanner.py
@@ -0,0 +1,111 @@
+from typing import Dict, List
+from collections import defaultdict
+import discord
+import re
+
+# Custom libs
+
+from logs import ChannelLogs, MessageLog
+from .scanner import Scanner
+from data_types import Counter
+from utils import (
+    COMMON_HELP_ARGS,
+    plural,
+    precise,
+)
+
+
+class WordsScanner(Scanner):
+    @staticmethod
+    def help() -> str:
+        return (
+            "```\n"
+            + "%words: Rank words by their usage\n"
+            + "arguments:\n"
+            + COMMON_HELP_ARGS
+            + "* <n> - top <n> words, default is 10\n"
+            + "* everyone - include bots\n"
+            + "Example: %words 10 #mychannel1 #mychannel2 @user\n"
+            + "```"
+        )
+
+    def __init__(self):
+        super().__init__(
+            has_digit_args=True,
+            valid_args=["all", "everyone"],
+            help=WordsScanner.help(),
+            intro_context="Words usage",
+        )
+
+    async def init(self, message: discord.Message, *args: str) -> bool:
+        self.top = 10
+        for arg in args:
+            if arg.isdigit():
+                self.top = int(arg)
+        self.words = defaultdict(Counter)
+        self.all_messages = "all" in args or "everyone" in args
+        return True
+
+    def compute_message(self, channel: ChannelLogs, message: MessageLog):
+        return WordsScanner.analyse_message(
+            message,
+            self.words,
+            self.raw_members,
+            all_messages=self.all_messages,
+        )
+
+    def get_results(self, intro: str) -> List[str]:
+        words = [word for word in self.words]
+        words.sort(key=lambda word: self.words[word].score(), reverse=True)
+        words = words[: self.top]
+        # Get the total of all emotes used
+        usage_count = Counter.total(self.words)
+        print(len(self.words))
+        res = [intro]
+        res += [
+            self.words[word].to_string(
+                words.index(word),
+                f"`{word}`",
+                total_usage=usage_count,
+            )
+            for word in words
+        ]
+        res += [
+            f"Total: {plural(usage_count,'time')} ({precise(usage_count/self.msg_count)}/msg)"
+        ]
+        return res
+
+    special_cases = ["'s", "s"]
+
+    @staticmethod
+    def analyse_message(
+        message: MessageLog,
+        words: Dict[str, Counter],
+        raw_members: List[int],
+        *,
+        all_messages: bool,
+    ) -> bool:
+        impacted = False
+        # If author is included in the selection (empty list is all)
+        if (
+            (not message.bot or all_messages)
+            and len(raw_members) == 0
+            or message.author in raw_members
+        ):
+            impacted = True
+            for word in re.split("[^\w\-']", message.content):
+                m = re.match("[^\w]*((?![\d_])\w.+(?![\d_])\w)[^\w]*", word)
+                if m:
+                    word = m[1].lower()
+                    for case in WordsScanner.special_cases:
+                        if word.endswith(case) and word[: -len(case)] in words:
+                            word = word[: -len(case)]
+                            break
+                        if word + case in words:
+                            words[word] = words[word + case]
+                            del words[word + case]
+                            break
+                    words[word].update_use(
+                        message.content.count(word), message.created_at
+                    )
+        return impacted