Certain filters are threaded, and others are OpenCL-enabled. So OpenCL and CPU-only tests are different.
Ahh, I thought it used both as I've seen some reviews on this website where software uses the cpu and gpu accelerated openCL together.
Also a weird thing I've noticed is that in this
article 7zip hands down beats every other program in both file compression time and size, yet in articles such as this one
winrar is faster by a factor of over 2. Why is there such a discrepency? The articles are even using the same versions of the program.