TL;DR
Add expire time for items on ground to despawn them.What ?
Add expire_time for "item-on-ground"https://wiki.factorio.com/Prototype/ItemEntity
I don't want to affect items on belts etc though.
Why ?
Some mods add so much loot that players don't pick them up. It piles up more and more without any limit.It's much more noticeable on servers with many players.
Sometimes players losing so much, some stuff generated by scripts don't have any "cleaning".
The more people on a server, the more such cases.
There are quite a lot of mods with loot: https://mods.factorio.com/query/loot?version=1.1
I'm not sure how much it affect on some stuff and on save file size.