I only had 10.5.7 on for a half hour.
Safari and Camino took a long time to load pages and was a few steps behind as I was typing. The beachball spun and spun. I had to Archive the old Operating System. I put 10.5.7 on because my keyboard kept freezing in 10.5.6. I'm still not sure if it was the OS or if the keyboard has issues. Too soon to tell. It never froze in earlier OS's. I won't go back to 10.5.7. I'll wait until the new OS comes out and they get the bugs out of that.
MacPro 3.2GHz