This change has been in the works for a while. The main benefit is twofold:
1. Improved performance. About 30% more fps
2. Elimination of jagged edge artifacts on particles
The graphics engine uses deferred rendering. There are 2 frame buffers that are required: Color and Depth. Previous Depth buffer was built in a separate rendering pass, which basically required the whole geometry to be re-rendered twice, once for Depth and once for Color pass. Now both of these buffers are built in a single pass which significantly increases performance. The artifact elimination comes from improved depth buffer precision.
A lot of players on integrated graphics cards have been reporting poor frame-rates, this update should help keep FPS more reasonable on lower-end graphics cards as those.
These changes will be shipped with the next patch. We’re still working on other parts of it, it should be ready in about a week.