Tekkit running very slowly

[dragonitrate]

I'm having some problems running Tekkit (and tbf any other Technic Launcher Modpacks) on my PC. It definitely isn't a problem with specs, as I'm running an Intel 4720HQ and Nvidia GTX 970M, which have no problems running any other game (GTA V, Civ V, CSGO) in Ultra settings at 60fps. The problem is that when the world loads, it runs at high fps (~60) but as soon as I start to move the frame rate drops to less than 10fps. It makes the game unplayable.

I have already dropped the settings to as low as they will go, set the process priority to high on task manager, installed optifine, and allocated more RAM (6gb) in the launcher, which are solutions other threads have offered.

Any ideas would be greatly appreciated.