According to benchmarks, you should be getting 30-60 FPS in Bioshock Infinite with everything on Ultra except for shadows (which are on high). If you are getting lower framerates than that, I recommend turning off vsync. If you are still having issues, then it has to do with your processor.
I recall my Phenom II 1045T at 3.5 GHz dipping into the low 20's with Crysis 2. I switched my GPU from a 5850 to a 6970 and received the same framerates after upgrading. I then upgraded my processor to a 2600k and started getting much better performance.
At 3/26/13 07:49 PM, ClockworkSpace wrote:
I think you need to upgrade to 8gb ram
The performance difference between 2 GB of RAM and 4 GB is phenomenal. The performance difference between 4 GB of RAM and 8 GB of RAM is negligible unless you are a scientist or high-res artist.