У вашего броузера проблема в совместимости с HTML5
I made a lots of Uncahrted 2 tests but this game always was quite unstable lots and lots of hangs. Elad one of RPCS3 developers made a PR that helps this situation.
https://github.com/RPCS3/rpcs3/pull/7233
The settings that was used for it is Driver Wake Up delay, setted on 350us, that cost me about 1 or 2 frames from 60.
As a result a whole Train level without a single hang and crash on Hard level.
My specs: i9 9900k 16 Gb Ram GTX 1070
My build:
https://mega.nz/#!KJxS0AiD!EFUIIr06G_WvpqPQgvO7TkoRm7FYiquYu-c7AoNej8k