Speaking of motivation...

From the SLDev mailing list:

I had 3 fps with Linden Labs 32-bit client for linux.
I then got the source code and compiled it for 64-bit,
and got 30 fps, on the same hardware...

Time to read up on how to compile the client. Of course, it's just about impossible to guarantee identical conditions--were similar numbers of users on? Did the poster go to the same place, under similar conditions?--but it's worth a try.