My game seems to suffer from constant "slow down spikes". ie. it would run at normal speed then dip down and accelerate back up to normal. This is most noticeable on scrolling combat text and the speed of the GCD. Fps is hovering between 5 and 15 in LFR.
My system is a 2009 Macbook Pro.
Processor: 2.53 GHz Intel Core 2 Duo
Memory: 4 GB 1067 MHz DDR3
Graphics: NVIDIA GeForce 9400M 256 MB
In 10.6.8, it was mostly fine. FPS was still low and in the 10-15 range, but it wouldn't slow down and speed back up.