You think it would lag less when you do that..not the other way around. That is very strange. Have you tried updating the browser you're using? It might be a bug on that particular version. You could try modifying your resolution to see if it still occurs. Perhaps you should run a system scan in case you have any malware or something nasty. Iv often found that my lag on games is based on unwanted software on my system usually caused by Advertisements that install add-ons/programs without your permission.
Or you could try changing your resolution although that shouldn't be a solution as it should work fine the way it is.
