Possible Fixes

Yes

Modpack Version

0.3.2

What happened?

I have done some tests in singleplayer ,and have found 2 mods (FTB Optimizer and Achievements Optimizer) that optimize both FTB Quests and the Achievement system and can solve the immense lag issue. The first image shows how laggy it is without the 2 mods installed.

The second image shows how much the lag is reduced with the 2 mods installed.

latest.log

No response

Developer reports

mekanism/Mekanism#7625

Downside is FTBQuests then takes an actual age to know that inventory changes have happened and to grant progression.