if you have a low-end PC (especially Intel integrated graphics), do this:
Required Changes:
Remove the mod Fusion (Connected Textures) — this was the main crash cause for many.
Set Render Distance to 4–5 chunks
Mipmap Levels → 0
VBOs → Off
Max Framerate → 60
Graphics → Fast, Particles → Decreased, Clouds → Off
JVM Arguments (Additional Arguments):
-Xmx6G -Dforge.forceNoStencil=true
(Use 4096 MB or 3072 MB if you get Java VM errors)
With these changes I get 55–60 FPS while moving on an Intel UHD 617 with 16 GB RAM.
which of 6gb is being used
Now enjoy the wonderful times of having a low end pc and also a good tech modpack(any suggestions on mods to add will be appreciated!)