I would translate that as ca. 8h?
That could be your problem, even though your information is quite vague. As others have pointed out, more precise information would be useful.
If you want some comparision… I have: Ryzen 5 3600, 32 GB, AMD RX 6600. Without OpenCL it would take ca. 1h 40m to export 500 photos with this processing pipeline:
With OpenCL it takes 40 - 45m.
When I now translate “old” with something like “2012” and suppose a midclass i5 mobile CPU or similar of that time, needing like 8h for 500 photos sounds reasonable to me.
About the comparison to the Sony software: That’s just how it is. DT isn’t the fastest.