“When I got my Dual Quad-core 2.8GHz Mac Pro running Mac OS X 10.5.2 with the upgraded graphics card, an Nvidia GeForce 8800 GT, I was disappointed in its graphics performance relative to my former MacBook Pro with slower graphics, an Nvidia GeForce 8600M GT. But I was hopeful that the subsequent update of Mac OS X would improve the Mac Pro’s graphics performance but it did not happen with 10.5.3 nor with 10.5.4,” Bill Fox reports for Macs Only!
“Apple released Mac OS X 10.5.5 on Monday, 9/15, with new graphics drivers so my hope of improved performance was again renewed. I installed Mac OS X 10.5.5 on a number of Macs: Mac Pro, MacBook Air, iMac Core 2 Duo, PowerMac G4 Cube and PowerBook G4,” Fox reports.
“Curiously, Mac OS X 10.5.5 is not only overall no faster than 10.5.3, it may be even slower for some graphics tasks,” Fox reports.
Full article, with benchmarks results of Mac OS X 10.5.5 vs 10.5.3 here.