Most tiger issues fixed in public beta
video and scsi drivers now fixed by apple.


You cant turn off spotlight -

Spotlight performance


There's one slightly dim spot in the Tiger performance picture, and unfortunately it's going to be a part of every user's first experience with the new OS. When booting into Tiger for the first time, Spotlight has to index all attached drives. This is done with a low-priority background task, but there's no avoiding the huge amount of disk activity involved. Expect your first few hours in Tiger to be accompanied by the steady tick and pop of all of your hard disks.
http://arstechnica.com/reviews/os/macosx-10.4.ars/19

and the scsi and video card drivers are broken.