Is it normal for the BIOS to slow down on the memory check by a lot when reaching 9.9MB? Up to that point, it goes very fast(about 4MB/s), but then it becomes many times more slow up to the end of remaining RAM?

Is that normal behaviour on a Compaq Deskpro 386(it's a J.4 BIOS ROM)? Or is this an emulation bug somehow?