** GENERAL **
First of all you should try to change the quality settings to ancient so see if that fixes anything.

** GENERAL ISSUES **
> Run the Game in Chrome
> VISIT: chrome://flags/ AND ENABLE THE --ignore-gpu-blacklist FLAG

** FRAMERATE LAG (FPS) **
Framerate lag will often be experienced as a constant jitter. This will most likely be due to a hardware or browser issue.
> Try running the game on Chrome
> Try running the game in incognito mode
> Lower the settings in the Options Menu found on the Menu Screen
> Disabled any Plugins or Extensions on your Browser
> Close any other tabs (In particular if you have a youtube video playing in the background)

** NETWORK LAG **
> If you are connected through WiFi. Check your signal strength
> Refresh the game as you might have joined a server in the wrong region (This would be an issue on my end)

If none of these steps have helped. Please post in the forum and specify in detail what kind of issue you are experiencing.