5zig is really helpful and is allowed on the server. For a full list of mods you can use click on the link below. http://itsjerryandharry.com/threads/detailed-rules.74449/
Why hasn't OptiFine been suggested yet? Easily the best mod out there when it comes to gameplay improvements. It's easy to install, it's fast and comes with more control. Here is a link to the mod's latest version (1.12.2, feel free to change this as you please): http://adf.ly/404181/optifine.net/adloadx?f=OptiFine_1.12.2_HD_U_C8.jar
I've used this, it's alright but it wasn't really better FPS with it, felt the same as if I was running 1.12.2 vs OptiFine 1.11.2.
Here is what I use, I use forge, where I have 3 basic mods running that helps me and doesn't really lag. I might get some potion effect and armor status to help also, so with these added, you should be good to go!