andreyf4, do you have any working example of this bug?
(e.g. at jsbin.com)?

Unfortunately, my working example is very complex.
But, in general, I drag with mouse on canvas and send websocket message on each mousemove event as well as some other websocket messages. I expect to receive answer on each message from server. I receive it only I stop dragging.

*Sometimes I get these answers messages but with big delay - several seconds and this delay increase when "dragging speed" increase

+WebSockets component.

A minimized reproduction would be very helpful here.

Are  issue 450258  and  issue 600385  related?

I found good example, looks like the same problem:
https://codepen.io/bQvle/pen/wGeqMG

andreyf4@ can you describe what you are seeing on the codepen? When I have the mouse down and drag the frame rate I see is constant.

Also it would be useful to know if this reproduces in Chrome Canary. We made some optimizations to the mouse movement pipeline that helps with latency. I don't know if that will help the websocket messages.

This is the video for my example:
https://www.youtube.com/watch?v=RsCpe6XOWuo

I found it here:
http://stackoverflow.com/questions/36212059/left-mousedown-mousemove-blocking-other-events-from-firing

*The problem doesn't happen constantly, sometimes is not reproducible.  

Could you try this on M55? We've adjusted the logic for throttling tasks since M53 I think.

This is reproducible for me at http://geoarena.online on Version 53.0.2785.116 (64-bit). Open a chrome window and then an incognito window, join a custom game from both windows so you're playing against yourself, then left click + hold + drag around. Same thing that happens in the youtube video linked above happens in game. Not 100% reproducible but definitely almost 100% reproducible.

I've tried on Chrome Canary (Version 55.0.2873.4 canary (64-bit)) and it seems to be fixed... any suggestions for how to alleviate this issue for now? 6 weeks is a long time to wait for a new Chrome version, and thousands of my players are hitting this issue. The only advice I've been able to offer is to switch to another browser for now since this doesn't seem to happen in any other browser right now.

Did you try M54? https://www.chromium.org/developers/calendar

M54 release is about 3 weeks away.

looks like this is fixed (at least for me) in M54, will wait for that release.

As per comment #12 this is fixed in M54.