[pjmlp]

AVX is the surviving heritage from Larrabee, the CPU that would outtake GPGPU and so far has failed to do so.

The only thing that Intel has going for their GPUs is that as typically happens with the underdog companies, they decided to play nice with FOSS drivers and with integrated GPUs they own the low budget laptop market.

Everyone that has done any serious 3D programming is painfully aware how bad their OpenGL drivers used to be, they even used to fake OpenGL queries confirming features as supported, when they were actually implemented in software, thus making some games unusable.

That is why they started the campaign about optimizing games for Intel GPUs, and how to make best use of Graphics Profile Analyser, which ironically in the old days was DirectX only.

The bottleneck you mention is only an issue when there isn't any shared memory available, if the hardware allows for unified memory models then there is no data transfer and the GPU can work right way, naturally there are some synchronization points that need to happen still.