Dear devs

I was just renaming a few dozen files in an album using the rename function. All I did was changing the extension to lower case, i.e. [name].[ext]{lower}. The process ran very slowly with a lot of HDD load. Apparently, the thumbnail is recreated for every image plus possibly some other database stuff (I saw the thumbnail DB grow while renaming was in progress).
From my point of view, should a simple changing of the filename reference in the database not be enough instead of creating a whole new image entry?

Thanks for your consideration.

Reproducible: Always

Steps to Reproduce:
Rename a bunch of files.
Actual Results:  
It takes quite some time and causes a lot of disk load.

Expected Results:  
It should be quite fast, because basically only one string should be changed in the database.