There was a similar update with 1.4 who brought very bad performance problems including low FPS and stuttering for alot of people also including crashing and texture glitches that are still not resolved right now. Make sure you test your patches appropriately before you implement them.
I had this problem big time with both my Nvidia and Radeon machines after 1.4 - still can't use my Nvidia machine even after the patches. For me, the problem seems to worsen as the number of players active in a given instance increases.
Even so, I must add that I love the graphics in the game and welcome the effort that goes into updating/improving them.
BUT each new update also needs to bring fixes to exisitng problems - nothing irritates me more (and it seems just about everyone else!) than when a new patch only adds to the list of exisitng issues.
I have been playing 1.5 on the public test server on and off for the past week - completed Tython and Coruscant so far. The graphics run considerably smoother (for me, anyway) on my Radeon than the current 1.4 version on the live server. Hope this is true for others trying it too. Still, there are considerably fewer other players active at the same time on the PTS.