This information applies to version(s): 5, 6
With macOS (v12.3) a regression was introduced, which considerably slows down the Apple Neural Engine cores used in all M1 & M2 Macs. This exclusively affects Fujifilm X-Trans RAW files in DxO PhotoLab.
UPDATE: since the official release of macOS Ventura, this bug has been fixed by Apple.
If you are still using macOS Monterey (from version 12.3 and up), there is a workaround to let you continue using DeepPRIME with great speed: go to the DxO PhotoLab’s preferences and under “Advanced/DeepPRIME acceleration”, manually choose the option “GPU Apple M1" (or M2) instead of the “Apple Neural Engine.”