a stated above it's hard to know if it's you project causing this problem without a capx. What kind of events are you using? Have you tried updating your GFX card Drivers? what are you running the game with(Browser)? what are you PC specs? Do they support WEbgl in your browser? what kind of downscale setting are you using in C2? what scaling?
We can really help without this type of info as it could be anything from you have a old pc to using a nonupdated browser