Extreme Slowness after version 0.31

Something has changed that has made reading a lot slower. I'm using pyaff4 to read full disk images. With version 0.31, it takes about 3 minutes to read an APFS filesystem randomly seeking into various offsets to read 4KiB blocks at a time. 
Same code with version 0.32 or above takes ~70 minutes to do so. 