Hey there I had a old system bundle lying around so for curiosity sakes I installed mountain lion 10.8.2 on it to see how well it coped, the specs are as follows.
motherboard - P5KPL-AM
Cpu - Core 2 Quad Q8300
Ram - 2X2GB DDR2 667MHz
Video - ATI HD 5570 1GB of Memory
HDD - Western Digital 160GB 7200RPM Sata ii
WIFI - Atheros AR9285 a/b/g/n
Once installed and I sourced all the device drivers the system felt really snappy despite its relatively low Xbench score of 90. (with multithreading and Hard drive benching turned off. For some reason Xbench crashes on 10.8 if multithreading is enabled) All the GUI effects seemed really fast and startup was fast as well. So after that i decided to reinstall 10.8.2 on my main system it didn't seems as fast or snappy as the Q8300 system at all, longer startup times and longer application start up times, and thats very surprising considering its specs
Motherboard - GA-H77N-WIFI
Cpu - Core i5 2500K
Ram 2x2GB 1600MHz Corsair XMS3
Video ATI HD 5770
HDD - Western digital 1TB 64MB Cache Sata ii
WIFI - Replaced MINI card Atheros AR9285 a/b/g/n (the original mini card that came with the motherboard wasn't compatible with os x
The Xbench score was 398 for this system (With the same two options disabled).
What I'm wondering is this, despite the fact the Q8300 is generally a lot slower than the i5 is it optimised in some way for faster smaller operations. and on the other hand if i used a multithreaded program the i5 would shine wheres the q8300 would choke. But on day to day programs the Q8300 seems faster strangely.