I ran it overnight and it only did 7500 selects in something like 10 hours. So something is horribly wrong, although "sfc /scannow" says everything is hunky dory.

This is a read-only DB and is a simple copy from the original. All nonessential services have been disabled on Win (eg. search and more). I did look at procexp and procmon before posting.

I have an identical machine with Win 10 Pro installed and will test there. Also may test read/write speeds of csv files to see if there are obvious disk issues that Crystal disk can't see.

Big thanks to everyone for your help!

Did you verify that the disk is indeed formatted with NTFS and not FAT32? Win 7 Disk Management can tell you that.

Don't know about Crystal disk benchmarks. I would try something simple, how fast can the DB be read?
>copy yourDBname.sqlite NULL on Windows, NULL is a reserved file name that means "the bit bucket".
See if there is any difference between the computers...

Perhaps some experimentation to see what kind of cliff you are hitting might be interesting...Make a DB 1/10 the current size and benchmark that - see if the 400 MB file compares ok against the other machines or not.