Bug Help with modpacks causing extreme lag

[JUSTCAMH]

It seems that on a lot of modpacks I get extreme lag, even on the main title screen. There's no accurate way of knowing, however it looks like I get less than 1 fps on the title screen. I do believe that this bug has something to do with a techy mod, as I tried playing FTB Mage Quest and there was no lag at all. I tried playing both agrarian skies and tppi and neither were even approaching playable. I have tried optimisation and it doesn't seem to be working. I have allocated 8 GB out of 16 and it is still causing lag. I used to have another computer that I allocated 2GB and the game ran smoother. No errors seem to come up on the log.