[Help!] TPS less than 1 in singleplayer world

[2003Alex2011]

I recently started a Tekkit Legends world and decided to manually add Galacticraft back into the modpack. I've been playing for around 50 hours. After returning to Earth from my space station, I noticed an insane dip in TPS. The /TPS command reveals a TPS of 0.3. I have no idea what caused this, but if anyone has any insight into whatever's going on, it would be much appreciated.

Information:

World Download: http://www.mediafire.com/file/3mk2wq3u5kesuyq/Tekkit.rar/file

RAM: Java using 3.4GB of allocated 3.5GB

If any more information is needed, I will add it here.