I don’t think this is an issue of the speed of the computer. These are poorly optimised core routines which will affect just about everybody, regardless of GPU or number of processors. I’m astonished DxO is adding features which slow the program further (slowness is what everybody hated about Lightroom 3 and 4 and 5, versions 1 and 2 are pretty spritely) like DAM before fixing core routines, improving hardware optimisation (particularly on the GPU) and adding newly released cameras.
If PhotoLab becomes this impossibly slow eight armed monstrosity, photographers will not be able to afford to use it. Slow post-production is both psychologically frustrating and a great thief of time.
If PhotoLab were the fastest post-production tool (C1 or Lightroom would win here now, both are pretty quick, sliders are mostly in real time) that would be an enormous win for the existing userbase and very attractive to new users. “Powerful but slow” is not attractive marketing for photographers. Most of us feel too much of our lives is lost in the digital darkroom already.