Just recently I noticed some issues with the ground texture on my computer.

 

 

As you can see, the texture (grass, etc) is messed up. Sometimes chat text (above player heads) can get messed up too. I don't think this is on Jagex's side because the beta server (which doesn't get updated) has the same things. How can I fix this? I've tried updating Java and playing on a different browser (normally I play on Chrome). I don't think other common quick fixes (clearing Jagex cache for example) would work here.

I've got the same problem, and bloom makes it even worse.  

I don't have this problem with the client. It's been happening for weeks on the french servers though along with lag spikes lasting as long as 5 minutes that are unplayable. Hope they get a fix soon for this. A quick fix is to put the game on OpenGL, but it'd be fun to have it back to DirectX soon.

So this is a problem many people are experiencing and has something to do with the game engine? Good, but why am I getting similar issues with the beta. The beta was fine when it first came out and has not been updated since, however I experience the same issue there.

I don't think the issue has to do with the game engine, I think it has more to do with directX itself.

Okay thanks.