Get the cooldown start time at the end of the upload, not when we receive a response from the server:

shorter cooldown period and faster auto-posting.

4chan_x.user.js

@@ -5849,7 +5849,7 @@
       },
       set: function(data) {
         var cooldown, hasFile, isReply, isSage, start, type;
-        start = Date.now();
+        start = data.req ? data.req.uploadEndTime : Date.now();
         if (data.delay) {
           cooldown = {
             delay: data.delay
@@ -5876,15 +5876,14 @@
       },
       count: function() {
         var cooldown, cooldowns, elapsed, hasFile, isReply, isSage, now, post, seconds, start, type, types, update, _ref;
-        if (Object.keys(QR.cooldown.cooldowns).length) {
+        if (!Object.keys(QR.cooldown.cooldowns).length) {
-          setTimeout(QR.cooldown.count, 1000);
-        } else {
           $["delete"]("" + g.BOARD + ".cooldown");
           delete QR.cooldown.isCounting;
           delete QR.cooldown.seconds;
           QR.status();
           return;
         }
+        setTimeout(QR.cooldown.count, 1000);
         isReply = g.BOARD.ID === 'f' ? g.VIEW === 'thread' : QR.nodes.thread.value !== 'new';
         if (isReply) {
           post = QR.replies[0];
@@ -6615,6 +6614,7 @@
         upCallbacks: {
           onload: function() {
             QR.req.isUploadFinished = true;
+            QR.req.uploadEndTime = Date.now();
             QR.req.progress = '...';
             return QR.status();
           },
@@ -6686,6 +6686,7 @@
         postID: postID
       }, QR.nodes.el);
       QR.cooldown.set({
+        req: req,
         post: reply,
         isReply: !!threadID
       });

changelog

@@ -16,7 +16,9 @@ beta
       Delete links in the post menu will only appear for your posts.
 
   QR changes:
+    Cooldown start time is now more accurate, which means shorter cooldown period and faster auto-posting.
     Clicking the submit button while uploading will abort the upload and won't start re-uploading automatically anymore.
+    Closing the QR while uploading will abort the upload and won't close the QR anymore.
     Creating threads outside of the index is now possible.
     Selection-to-quote also applies to selected text inside the post, not just inside the comment.
     Quoting the OP will not insert the >>opnumber anymore unless the QR was already opened.

src/qr.coffee

@@ -159,7 +159,10 @@ QR =
         QR.cooldown.cooldowns[id] = cooldowns[id]
       QR.cooldown.start()
     set: (data) ->
-      start = Date.now()
+      start = if data.req
+        data.req.uploadEndTime
+      else
+        Date.now()
       if data.delay
         cooldown = delay: data.delay
       else
@@ -186,15 +189,15 @@ QR =
       delete QR.cooldown.cooldowns[id]
       $.set "cooldown.#{g.BOARD}", QR.cooldown.cooldowns
     count: ->
-      if Object.keys(QR.cooldown.cooldowns).length
+      unless Object.keys(QR.cooldown.cooldowns).length
-        setTimeout QR.cooldown.count, 1000
-      else
         $.delete "#{g.BOARD}.cooldown"
         delete QR.cooldown.isCounting
         delete QR.cooldown.seconds
         QR.status()
         return
 
+      setTimeout QR.cooldown.count, 1000
+
       isReply = if g.BOARD.ID is 'f'
         g.VIEW is 'thread'
       else
@@ -826,6 +829,7 @@ QR =
         onload: ->
           # Upload done, waiting for server response.
           QR.req.isUploadFinished = true
+          QR.req.uploadEndTime    = Date.now()
           QR.req.progress = '...'
           QR.status()
         onprogress: (e) ->
@@ -912,6 +916,7 @@ QR =
     }, QR.nodes.el
 
     QR.cooldown.set
+      req:     req
       post:    reply
       isReply: !!threadID