I've already stated several times across both of these threads what needs to be done, at least as an attempt/test to try and alleviate this issue. We all know part of it is poor video card drivers. Nobody's disputing that fact. There are two other parts: One is the lack (or lack of proper coding for if already implemented in the GLL backend) proper GPU/CPU synchronization, which is enabled in one of the functions for OpenGL 3.2 or 3.3 (can't remember which offhand).
The other part is the lack of available texture cache for palette/texture swaps on the fly that aren't agonizingly slow. On video cards with 1024 MB of VRAM, the OS requires double that in system RAM for the very specific reason that it needs at half of ithe availble (assuming minimum required) RAM for texture mapping. The OS never runs into these kinds of stutter unless the video card driver is really in bad shape (that has happened a few times in the past even on Windows), and this is because it can use as much RAM as the card has for its VRAM in order to facilitate texture swapping en masse (say, on switching users, using Expose, or spaces). WoW currently has, at least as of 4.0.6, a limit of 64 MB of texture cache. That's a paltry 1/16th of the top of the line Mac video card right now in terms of RAM. So while the FoV may use more than that to store textures, only 1/16th of the total VRAM on the top end cards can be swapped out in any given moment. That's a huge bottleneck, especially considering 64 MB generally doesn't even cover the FoV in front of the player fully, thus whenever we turn, we stutter as new textures are reloaded into VRAM from either HD/SSD or system RAM. Thing is, it happens so often that reliably playing just isn't feasible on Ultra. And even if the texture cache were doubled to 128 MB, that's 1/8th the possible VRAM high end cards use right now. So if the area you're in uses say 512 MB of VRAM, in 4.0.6's client, if you spun around a full 360 degrees, you'd have to texture swap eight times (8 x 64 = 512). It'd be at least four full swap cycles even with 128 MB of texture cache.
Then you run into the stack heap (app RAM which includes the texture cache) running dangerously low as it closes in on that magical 2 GB barrier. With a 64 MB cache we were already hitting 2 GB (and crashing from it) on Ultra. Those crashes would happen sooner rather than later if the texture cache were bumped up any. But with the full 4 GB RAM available to the app via PAE, the texture cache could be a full 1 GB (1024 MB) and that'd still leave the app 3 GB of RAM for other uses, which is a full gigabyte more than it can use right now. So that'd be 3 GB RAM (no texture cache) + 1 GB texture cache as opposed to 2 GB on Live, which includes the texture cache in that amount.
I know changes aren't always easy - anybody that's ever done more than a Hello World coding project knows that. But the changes to give WoW the full monty when it comes to resources has to be less painful than trying to kludge a larger texture cache into an already full plate of RAM use. It's like trying to stick bacon and eggs with your english muffin onto that tiny bread plate which normally houses the english muffins only. You can do it, but you'll either sacrifice quality or quantity (or both). Realistically you need a bigger plate. And that's where we sit. Our plate is too small to hold what we're trying to eat.