[SelfEnough]

It only takes a second or two to rename the tvshows folders, but it takes several minutes to rename the movie folders.

Every time I organize my movies, I just rename the folder, not the media files.

But every time I run renameing， it's very very slow 

Can't you use the tvshow's mode when renaming a movie?? which is fast

[mlaggner]

renaming movie folders is a bit more complex than renaming TV show folders (because you would be able to put several movies into 1 folder whereas you only can put 1 TV show into 1 folder), BUT in common this totally depends on your storage/setup.
I can just say that I often rename my testbed on a NAS connected via LAN and there is no slow down..

If you are on linux and accessing a NAS please make sure you don't mount the NAS via KIO/GVFS -> mount it via /etc/fstab (just search the forums, there are several threads about that topic)