How do mods effect the RAM usage?

I'm renting a server with 4Gb RAM. Have a few mods, would like to install a few more, but am afraid that it'll make the server laggy. Read a lot of discussions on how to cure laggyness - it's all very confusing.

It would be nice to know once and for all if mods severly effect the RAM usage?
If so, which ones should we avoid installing?

 

There is only one way to find out for sure - install what you like, one after another, and watch as players go online how your RAM usage develops.

There's plugins that need almost no resources at all, both CPU and RAM wise, and then there's those that can have quite an impact, depending on other factors like map layout(s), number of players etc. Obviously, some tasks take much more computer resources than others, and it also depends on how well the programmer implemented it. But there is no "this plugin needs 1 GB WAM" rule or list you can look up.

 

4GB could run 60 light plugins or 30 heavy ones and 80 players.