Technical suggestion / idea / observations from the low end of the graphics card pool.
So I was playing around for about an hour, maybe more, this afternoon on the "entry" level. Before the rescue camp.
My graphics card is a 9550 mobility; my driver is the 10.5.8 mac os driver. (On some crashes, the driver logs itself as the 9700 driver.). Resolution used for the test was 800x600, full screen. Vertical sync was turned off.
If I had either medium, or high, level of detail, the performance is the same. Entering a new area can have a significant delay, apparently as stuff is loaded into the graphics card. Once loaded, I have reasonable frame rates.
If I drop to low level of detail, then I get good frame rates. Significantly better performance.
Surprisingly, after spending a LOT of time looking and watching, I did not see any noticeable frame rate difference between compatibility mode on and off. The test was running from the crash pod until the straight north/south run that crosses over the chasm showing the clockworks, as well as just that north/south run from end to end. (So both a short run, and a long run). Note that this test includes a camera angle change, so I can see frames even if I stand still.
In battle, frame rates were bad, worse in medium/high, and dependent on number of enemies.
I had horrible frame rates in only two types of cases, and the resolution (low, medium, high) made no difference: Monster spawn, and "new terrain" (such as entering the gears area).
I don't know the details of programming a graphics card. My OS background has been all about keeping user-land away from the hardware, and making a single piece of hardware appear to be available to all programs as their own; graphics seems to be about letting programs have direct access to the card, and being able to own parts of it. So I really don't know how much of what I'm about to say makes sense, or is possible.
I think that response can be made significantly better by loading graphics, animations, and images into the graphics card before they are needed. As a prefetch, or preload. As a background thread; instead of a big delay when loading when you enter a room and things spawn, the server responds to "moving towards room X" with "Preload these on the assumption that they will be needed".
The expected result: When the monsters spawn, there is no "big delay", but the card can respond quickly, with everything already loaded.
With "All party" buttons, there is another issue. They come in two types that I've seen so far: Switch to a new section of the level, or begin a big battle. For the "begin big battle" buttons, you can do something else of value: Start loading the graphics into the graphics card. Do not actually activate the battle until all clients report that they are ready.
In other words, change the "Activate button" criteria from "All party members on the button" to "All clients report ready". When all party members are on the button, and not all ready, clients would have some sort of indication (putting "waiting..." on screen, or "loading...", or something; or perhaps something else.)
(If I could change my graphics card, I would have long ago. Neither the 9300 in the mac mini nor the 9550 in the iBook G4 can be changed.)