Many players have experienced faster WoW loading times with Windows Media Player (WMP) running in the background. Some players are also reporting lower latency and higher frames per second.
This tip surfaced in the Europe forums late November and was picked up by the US forums two weeks ago. Many players are reporting shortened loading times, some by more than 50%.
I did a quick test and found that by running WMP in the background, minimized and not playing anything, the login screen popped up about 20 seconds quicker than usual. The world loading time (time between clicking Enter World button and character appearing on screen) was also faster by about 15 seconds. However I did not see any significant improvements in latency or framerate. To eliminate performance boosts due to caching or preloading, I rebooted my machine between each set of timings.
Some players have also suggested adding:
SET timingMethod "1" or SET timingMethod "2"
to the config.wtf file to achieve the same effect without running WMP. For me, this shortened the time for the login screen to appear by 20 seconds as well, but only shortened world loading time by 5 seconds. Combining WMP and the config.wtf tweak resulted in the same timings with just running WMP alone.
There's been no official Blizzard response to this yet, although a likely explanation is that WMP modifies how your computer handles background applications. With WMP open, all available CPU resources apparently become allocated to WoW, leading to better performance.
Does this quirk work for you? Do you see any improvements in framerate and latency?