I think it would be nice to be able to (pre) compute all thumbnails for a a given directory/library/whole seafile. When the seafile is running on a low power system like a Raspberry Pi there isn´t a lot cpu power. If you browse e.g. your automatically backuped camera photos it takes quite a while until the seafile server generates the thumbnails for your (probably) high-res pictures.
It gets even more annoying when you scroll down and the process starts again. Wouldn´t it be easier to tell your seafile (maybe via cron (?)) to (additonally) tell your seafile server to scan for new files and to generate thumbnails every day/week/hour at a specific time to safe time later when it´s really important.
I heard that there´s already a api for thumbnails - maybe it´s easy to implement