Comment by dathinab

I assumed the OP/comment means "software vs. hardware accelerated rendering" when they say "it uses the CPU. And iGPU is still hardware accelerated rendering.

But some modern video codecs are designed to work quite okay with software rendering, especially if it's lower resolutions, and modern higher end dGPUs often have a pretty high "power overhead" on low utilization. To add to it the driver might keep it in a more high power state then strictly needed due to "expecting" more utilization, or similar.