This should be an optional change that people with powerful computers and smaller libraries shouldn't have to use patches to fix. For example, I have an HP Omen Transcend 14 with an Nvidia 4070, an Intel Core Ultra 9 185H, and 32 GB of RAM. I also have one gig Ethernet. Considering the fact that my book library is only about 100 books, assuming that they are all the same size and that we have the same computer/internet speed, if it took 1 second to transfer 100 books, it would take 45 to transfer 4500. That is not even considering the fact that @gerhaher has a really slow computer. This should either be configurable, or at least dynamically calculated relative to total filesize/file count, as I highly doulbt that more than 0.5% of people have more than 1000 books, so if something does have to be fixed with a patch, the 99.5% of people shouldn't have to do it it should be the 0.5%. After all if every company were to change things that only benefit 1 or 2 users, and bother the remaining 100,000 that just wouldn't work.

This as nothing to do with network speed, or book size. Increasing the no-activity timeout wont have any impact on the time it take to connect to Calibre, or transfer speed.

In the eventuality that Calibre appears to be dead, the "Disconnected from calibre (no activity)" will now take longer to appear. That's the only impact.

Isn't that how long it stays frozen before giving up? A minute and 15 seconds of a frozen screen seems like overkill.