My suggestion is simply an option to lower the detail of spell effects, especially AoE to more of a bare minimum, non-animated form, maybe all the way down to just a red or white ring with an icon in the middle for the AoEs which seem pretty heavy on shaded effects in their default form.
I’m not sure is this would be hard to implement, but I think it would make a huge difference in the playability of WvW for a lot of people. I have a mid-range machine and the game is very playable except for large WvW battles, where even with the settings turned to lowest it turns into a catastrophic slideshow of AoE spell effects when two large groups engage.