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Dunno...Leopard has been a major speed boost for me. Original 24" iMac here with 2 Gigs of RAM.

I mean, it's like night and day between Tiger and Leopard. It's like it's almost instant with the stuff I do. Spaces goes right into the next space. No graphic tearing or anything.

I thought Tiger was fast, but have been very impressed with Leopard. But as others have mentioned, this seems to be a Macbook issue more than anything.

Also, I Archived and Installed here.
 
Did an upgrade install on an original 2GHz MBP with 2Gb RAM.

Initially sluggish for Spotlight indexing and a non-responsive Last.FM process which was promptly deleted.

Works well now; however, it doesn't seem any faster or any slower.
 
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