@NiLuJe: I looked at your PR#2 and noticed you only wanted to speed things up when updating with the calibre plugin
.
I tried to shift the detection of actual changes in the Ebook and Collection classes, so that both sources of updates can benefit from this. I pushed an update that should achieve this: in my tests, updating twice from the same source does nothing the second time. Still, could you check if it works for you as in your PR?