Performance debugging ideas?

[seebs]

Okay, I confess myself stumped.

I have a medium-large collection of addons (maybe 80-100 directories in addons/, but some are libraries or multipart addons like auctioneer).

My CPU's a phenom II 940, I have 4GB of memory, and my GPU's a Radeon 9800. I run under WINE. I get a pretty solid 60fps in the old world, and 20-35 in Dalaran, depending on which way I'm facing.

Here's what bugs me: Those numbers are apparently unaffected by anything I can do.

All effects at max? 60fps old world, 20-35 Dalaran.
All effects at minimum? 60fps old world, 20-35 Dalaran.
Antialiasing 4x? Same.
Antialiasing 1x? Same.
Swap in a GTX 260? Same.
Turn off all addons but a frame rate counter? Same.

So what on EARTH is happening here? If it were GPU limited, I'd expect that a higher-end video card would help. If it were CPU limited, I'd expect that turning off all addons would help.

I'm stumped. I can't figure out anything that affects this.