So after the 0.1.7 patch, the game was causing me and others lag as we joined, and even as we we in the title screen. So I tried Optifine, which doesn't fix it, and FastCraft, which has no accessible download ATM. So I got creative. If you need to reduce your lag, you will need access to another 1.7.20 pack WITH FastCraft installed. Then you just drag and drop. Once you reload Hypo, it should not make you update, and you will be able to join lag-free.
FastCraft has no "accessible download"? It's right there: [WIP|1.7.10] FastCraft 1.23 (Note: All Posts of new Members need to be approved first, so if you press the submit button but no new post appears here, it is in the folder of posts to be approved first, and Player will receive them a few hours later) - Off-Topic - IC² Forum I had a very similar issue too, which was fixed by FastCraft indeed. Wondering what would be the cause...
Fastcraft is easy enough to add we had to remove it due to it crashing with another mod we have installed.