* If you are having GC problems: Disable natural mob spawning /gamerule doMobSpawning false This is extremely noticeable even in vanilla, the memory allocation rate drops off dramatically.
* Setting the “Max Framerate” option higher will make the game lazier at rendering loaded chunks (which I consider a bad thing)
From /u/entirelyUnoriginal (reddit)
world pregen can now be done with ChunkGen rather than the command block method (no need to remove railcraft or have client open). There were some issues with other versions but 1.5.0 worked flawlessly for me on a fresh world as of ATM 1.56
Try changing the Mipmap levels to 0(This may freeze up your pc for 10 minutes but it will eventually change) Disable/enable VSync & VBO’s.
You can also edit this in the packs folder and editing the Options.txt
Allocate more RAM
You need at least 4.5 Gb for this pack but 4.5-6 Gb is better for performance. 3-4 Should be fine for the Lite version.
Make sure you are using Java 8_91 64-bit or above to be safe. (make sure minecraft is closed while changing.
Make sure you play around with everything but turning Terrain Animated off is the important one. This may cause other issues but sometimes it’s needed. Downloads
Make sure to read over how to change profiles.Curse Page
Pre-Generate your World (obsolete, but still works)
This video should help you a ton!Youtube You may have to disable Railcraft before doing this, then add it back after. Note that a different code exists for 1.11 and above. Here is the Pastebin link. http://pastebin.com/fVrygaNG