I just joined a guild that uses this addon to organize guild events. It's a nifty addon, even if I didn't have to use it to sign up for raids, I'd want to, it's convenient.
Unfortunately the cost of this convenience is a LOT of memory. Just idling around talking in chat, not actually using it, the addon will quickly climb up to 10MiB. That's huge, for me anyway, my #2 is Ace2 at 7MiB, #3 is PitBull at 3.3MiB, nothing else I'm using even breaks 3MiB unless I'm using Recount or something to store data.
Is there any addon in existence right now that interfaces with GroupCalendar but uses less resources?
Your guild actually uses it to organize events? My guild tried to, but we quickly discovered that it's quite buggy and won't properly sync between users that someone has signed up for an event. Some still use it as a cutesy tool to notify about birthdays and such, but in our experience its use as a sign-up tool for events failed miserably.
There's also GuildEventManager (GEM), but from what I've read it's even worse than GroupCalendar.
I just installed this and after a few minutes all guild events synced--at the time around 5 of them-- and I didn't notice anything abnormal as far as memory goes. My memory was right where it had been before I installed it, so I figured it was alright. But maybe I'll look into that more deeply.
Our guild uses GEM and works reliably for signups. It does have some quirks that you have to be aware of or it won't work properly. The most important one is that you have got to be in a blizzard default channnel. I have no idea why, I just know that if you are in your GEM channel and not a blizzard default (like trade or something) you won't sync correctly. Also we never got the addon guild channel to work, but we didn't really try either.
We tried groupcalendar, but found it was worse than GEM for our needs and yeah wow, huge amount of garbage creation.