Bioshock Infinite's stutter has something to do with how the game loads textures. It seems like the game is trying to load too many textures at once and is overwhelming the graphics card - even the higher-end ones with 1.2GB to 2GB of RAM.
You can give your graphics card a little breathing space by increasing the Poolsize it can work with. This requires editing the game's .ini file, so a word of caution: make proper backups before attempting the following step.
- To increase the Poolsize, go to C:\[User Account]\Documents\My Games\Bioshock Infinite\XGame\Config and open the XEngine.ini file in a text editor (preferably Notepad).
- Search for PoolSize and change the value from the default 400 to 640. Save the file.
This fix has had the highest number of success rate among players. However, from personal experience I would say skip this and the next step as it caused my game to glitch out upto an extent that it would fail to load objects, NPCs and vital game moments required to further the story.
fixed the stuttering problem for me and I disabled vsynch as well
http://me.ign.com/en/feature/9145/fi...-stutter-on-pc




