I've got one user on my mail server with ~3,500 appointments in their calendar. The .json file for the calendar is 67MB. There's a warning that the file should be under 15MB or it will cause performance problems. The .json file used to be about 130MB, but I deleted a few thousand appointments.
Short of manually sorting older appointments into multiple new folders to keep individual size down or deleting old appointments, there's not really much I can do to get it any smaller.
So I'm curious if anyone else has a large calendar and whether they have an oversized .json file to go with it?
To check, with a Linux server, you go to /var/lib/smartermail/Domains/domain.tld/Users/username and check the file sizes of all your folder*.json files with:
ls -lah
To check which folder is which, run less on the folders.json file. Then search for "Calendar" and check the "id" in that block. That'll give you the filename of the .json file for the folder named "Calendar".
To check how many appointments you have, I recommend using jless to examine the .json file. It's performant even on huge .json files and you can quickly collapse everything to tell how many entries there are.
Has anyone got more than 4000 appointments? How big is your .json file?