Using a second partition D: is already twice as fast at small-file-writes compared to the system partition C:. This was on Windows 10 with both partitions using NTFS on the same SSD, and everything else on default settings.

This is because C: has additional file system filters for system integrity that are not present on other drives; and also because C: has 8.3 name compatibility enabled by default, but additional NTFS partitions have that disabled. (so if your filenames are longer than the 8.3 format, Windows has to write twice the number of directory entries)

It's shocking how much performance you gain by temporarily turning off Windows Defender. I had a local disk to disk copy that the Windows File Transfer dialog estimated was going to finish in 10 hours after it settled down. It wasn't even that much data, just a few hundred GB, but that consisted of a great number of small files. On a hunch I tried disabling Windows Defender and the estimate dropped to about 30 minutes, and in the end it was spot on.

More people need to know how this, it is absolutely bonkers how much perf you lose for each file open operation to defender and its kin.

Even excluding directories (like D:\MyProject) from defender isn't a full solution, the fs filter will still use the file handle to do lookup of the file path to see if it is in an excluded directory (at least on win10), but excluding an entire drive (like D:\) does solve this.

I have found that adding git.exe to the process exclusion list makes the biggest difference here, although git is still slow when dealing with lots of files, it goes from unbearable to bearable.