Peter, this is roughly a duplicate of the Required’s request here: GPU Acceleration. With GPU acceleration and intelligent proxies (what you are asking for), PhotoLab will run spritely enough to edit photos efficiently.
I’m worried we’re splitting the vote for proper performance optimisation. Hopefully DxO will get the message about how strongly their existing users feel about performance. It would be a pity for PhotoLab to become known for its quality but its unusable in a professional setting sluggishness.
Note, other users with large files are complaining about PhotoLab 2 performance. Not just Alec Kinnear with his 5DSR files and Peter (I’m not sure what your primary camera is actually).