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.