[Stefan]

GPUs continue to get more powerful at an amazing rate. The performance boost is not evenly distributed though. While ALU power is shooting through the roof some other parts of the chip are lagging behind.
Most notably lagging are the ROPs. A Radeon HD 4890 has 16 ROPs, which is the same as even an old X800XT...
Particles are often rendered as simple quads. This is particularly wasteful of our limited ROPs.

Read full story at Humus' site.