SQLite 12 times slower on Mac than Windows

My app uses FireDAC (Delphi XE7) to access SQLite.

The Mac version is about 12 times slower than the Windows version.

I have journal_mode turned off, and no journal files appear.

The only difference I can see is that the Mac has checkpoint_fullfsync turned on by default (it's turned off by default in Windows). I've turned it off on the Mac but the 12X slowdown persists.

What would cause such a huge difference in performance?