I haven't been running much Collatz lately with the Einstein 135th birthday challenge and this is the first time I've had a chance to check on its performance while running on my HD4000. I can see right now it's running .497 cpus +1 intel_gpu.
The app is "solo_collatz 6.04 (opencl_intel_gpu)

I dont have much a recent collatz history so I can't even compare to nvidia gpu atm but this is what I get:
18,177.57 .... 15,461.43 .... 7,438.99 solo_collatz v6.04 (opencl_intel_gpu)
5 hours for ~ 7500 credit. Gpu-z says the HD4000 is running 97-98% load, according to open hardware manager CPU graphics are drawing ~13.8w (i think 15 is max), so far this app saturates the igpu the best, i know seti and einstein loads jump around a lot but that could be the nature of the work.

Just looking for some iGPU comparisons if someone could share. This is a single thread, no concurrent work on the igpu, its on a i5-3570k @ 4.2ghz with (gpuz says 10mb dedicated and 68mb dynamic ram)