It works great on WSL2, if your IDE (or editor, which can be the same Emacs) is also inside the WSL environment.
I don't remember how the performance was in WSL1 (I switched as soon as WSL2 was in the insider build, for unrelated reasons), but I vaguely remember it worked ok, as in performance was snappy just like on native linux. (The repo is of comparable size, 2-4GB)
I think this warrants a bug report for palemoon