Lagging in a weird way

[Josh Mackenzie]

When I make a new modded world, (not my main one), every approximately 5 seconds, the screen freezes for another 4 seconds or so. I believe this has to do with world gen, as my main modded world was originally made in vanilla, with vanilla world gen. Is there any way to fix this?
Thanks

[Josh Mackenzie]

Where can I find the JVM arguements?

[Josh Mackenzie]

Sorry, but I still don't know where exactly to look

[Josh Mackenzie]

JVM arguements: -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M

Debug log attached

debug.zip