So I'm running Dell L702x 3D, same problems, disabled Hardware Acceleration which works great..
I have a dedicated GPU (GT555m) which is most likely the culprit if acceleration is the issue, It's likely the cause of having a GPU that isn't supported directly by OS X.
It could also most likely be software, I updated Flash to 13.x Beta and Firefox works fine now but Safari is still effed (purple/green flashes) and Aurora (Firefox Alpha) doesn't work either which is strange... I'd give it a few versions.
I'm not sure what you guys mean by responsiveness issues, the hardware acceleration turned off works just fine, YouTube's new layout loads very smoothy... it's very possible you have graphical issues? Since all video drivers are native in 10.9.X, I'm sure it's causing a ton of problems, my hackint0sh worked much better in 10.7.4 and 10.8.2 with modified Nvidia kexts, since 10.9, I can't even play LoL anymore without constant stuttering...