There is a link to a Google spreadsheet where the performance of GPUs (and others, like CPUs, PhotoLab versions 4 and 5, and so on) are compared on test images.
This topic, and the corresponding spreadsheet are very informative.
For example, the FP32 score of the GPU is the best indicator for guessing the expected processing time.
Target at least 3 500-4 000 GFlops, i.e. Nvidia GTX 1060, GTX 1650 Super, GTX 1660, RTX 2060, RTX 3050, or AMD RX 5x00, RX 6x00.
Please note that the version of PhotoLab (4 or 5) has a big influence on the result. The update of the GPU with the latest driver is also important.
PL5 DeepPrime took 14 seconds to process a 20mp DNG to Lightroom on my Windows 10 machine with a Ryzen 5 3600 and a GTX 1650 Super GPU-- barely entry level at this point. I switched to an RX 5500, which is in some ways an even lower spec’d card (and relatively cheap at the moment) and processing time was cut in half. The benchmark Egypt image took 17 seconds to export to JPG, down from 27. So the promised PL5 optimization for certain cards, even lower-end ones (but not including the GTX series) is real.