Locking for 5 minutes is abnormal. With auto-write xmp enabled it should just tag the files for xmp writing to be done leisurely in the near future (in the background) and not interfere with anything, whether it's trying to do it for every incremental movement or not.
That said, I recommend leaving auto-write xmp off anyway. Why?
You've already got current settings in the catalog. If you only save
xmp manually, after milestone editing and inspection of images,
then you are guaranteed xmp does NOT included the same goofs
your catalog does (or might). If you never goof, then please identify
home planet, cause it sure ain't Earth, and you sure ain't human..
So, my advice? - have a "finalization" procedure - when done editing
images, for now anyway:
* inspect image edits..
* save XMP.
That way, if ever you need to fall back to a "milestone" state which isn't
in backup catalog, you can just read XMP.
Cheers,
Rob