I think so. It used to work fine but until a few weeks ago it stopped. It used to take about 5 to 10 minutes to get the 'OK' output. With 'ls -R' it takes less than 3 minutes.
I'll take a look at it later. I'll keep this post open, even though I got the answer I wanted, so I can post my results using async.
Well, I might be sticking with the 'ls -R' because it's much easier to run that command on /mnt/ with multiple rclone mounts at the same time (instead of having running multiple "vfs/refresh" commands on the different mounts with different ports, even remove completely the 'rc' flag on the mount, it's probably a much cleaner way. But it won't stop me from trying out 'async' on a different machine.
@ncw , can you confirm that, let's say a directory has 5 hours left before it becomes uncached, but then I access it. Will it "refresh automatically" (even though I access the cache) and make it 24h (given by the --dir-cache-time flag) again ? Or it only refreshes when those 5 hours end, then the next "access" will be slow (getting the dir from Google) and cache it after it gets the directory ?