Despite the game running at perfect 60 fps, I was suffering mild stuttering/frame skipping. After tinkering a little with the game's files I found out that setting Torchlight's affinity to a single cpu core fixes (or at least helps) the problem.

To set the affinity, run the task manager (ctrl-alt-del) after launching the game and right click on torchlight.exe in the processes. Check a single core and click ok. Alt-tab back into the game. This must be done every time you launch it.

Tested on:
Win 7 Professional 64bit
Phenom x4 965
Radeon 5770 1gb
4gb ddr3 ram

Hope it helps.