I am not sure what we are comparing here so sorry if this is not relevant.
In my large calibre library, moving from one edited fied to another takes approximately 8 seconds. In a smaller library it seems instant. However in the large library editing metadata and going from one edited record to the next seems instant and the changes show up in the GUI instantly. The only delay is when I exit from the edit metadata dialog to the GUI and it is still much shorter than the delay in moving from edited field to another field in the Gui.
Same 2 databases, converting 100 books takes upwards of 30 minutes in large library and calibre is in a non-resnsive state for about 10-30 minute after the job number is zero.
Calibre stops responding during the entire process and I am lucky to be able to play Solitaire
The little icon in the corner does not whir around and clicking anywhere gives a white screen flash.
Same task in smaller library with same books takes less than 10 minutes total and both calibre and other programs are not noticeably slower. The little icon keeps whirring and I can view the job list etc.
I don't see this as a database problem, but I am not an expert.
Not complaining mind you, as it is my choice to have all my books and documents in one library.
Helen