[BetterRed]

@Joanna - I have a library with 6 icon only columns, 3 are based on whether the underlying data is empty or not (i.e one rule), the others have 3 or 4 simple rules. Number of books is 74,000. some of them contain +300MB video files. I do all my metadata editing in the book list table, I've not noticed this library is substantially slower than smaller less complex libraries.

Do DaltonST's suggestions to vacuum the database and defrag the library files.

Try hiding the Tag Browser - Shift+Alt+T to toggle

You can use the View Manager PI to help determine if certain columns are the problem. Create a new view that only includes the 'standard' columns you want, assuming that's quick (if it's not then the cause presumably lies 'outside' the library), and then select additional columns progressively, I'd start with the 17 rule icon.

I have a vague memory that colouring individual cells (rather than the whole row) effected performance - my guess is that would have been pre version 1.0, so it may not be true today.

When you edit metadata in the book list I believe every cell you edit writes a new metadata.opf file, the writes are done via a queue; so, in and of themselves they don't create delays, but if your AV were to lock and scan the file every time it was written then that may effect performance. But that would not explain why scrolling through the book list is slow.

BR