I'm playing single play on FTB using the Magic World 2 mod pack for 1.6.4, and I get really bad block lag. The chunks don't load, leaving blank blue space every where, animals don't move and if I break a block it doesn't give me the block and it doesn't come back even after a few minutes. It's fine by my base, I don't get any block lag, but if I go to a nearby Magical Forest biomedical from Thaumcraft 4, the block lag starts. It wasn't always like this. When I first started the world I could go anywhere without block lag, then it suddenly started while I was playing.
If anybody can help, that would be very much appreciated. Thank you.