Stuttering, Small freezes and framerate Issues

[spidernetlabs]

I want to report my situation with this issue:
first of all the game runs on a mid 2010 iMac with these specs
OS: Mac OS X 10.7.5
CPU: Intel i3 540 3.06 Ghz
GPU: ATI Radeon HD 4670 256Mb
RAM: 8 Gb 1333 MHz DDR3

Resolution: 1920x1080 (native)

and with these settings:
Resolution: 1920x1080 (native)
Texture: Medium - Bilinear
Shadow quality: Low
Shadow resolution: Low
SSAO: Off - Resolution Medium, 4 samples
Anisotropic: Off
Parallax: Off
Antialias: Off
V-Sync: Off

Everything else is On.

During the first level I encountered some minor lag/stutter as I mentioned here. I played another 2 maybe 3 levels and the stutter became higher. Then I noticed that jens said that reducing MaxChannels, StreamBuffers and StreamBufferSize could help*. And it improved the frame stability a bit.
Today the game was updated with a patch that introduced a video setting called "Adaptive V-Sync". So I decided to give it a shot. While Adaptive V-Sync was enabled I noticed some improvement. The game still stutter some times, I think it's my GPU fault, but the frame drop is not that high. So the issue it's still there, but at least I can enjoy the game.


*Open main_settings.cfg file with a text editor and change MaxChannels="64" StreamBuffers="8" StreamBufferSize="262144" with MaxChannels="32" StreamBuffers="4" StreamBufferSize="131072"