git garbage collection takes forever

My IntelliJ project is connected to a large git repository. When I startup IntelliJ, it starts a git process that appears to be git garbage collection (git gc). When I run "git gc" from the terminal, it uses 8 threads and still takes a couple hours to complete. The "git gc" process started by IntelliJ only uses one thread, which I've left running for two days now, but it still isn't finished.

Is there a way to prevent IntelliJ from automatically running "git gc" or a way to increase the number of threads it's using?