I tried playing the Big Dig modpack several times, but ever since it was updated for 1.5, it started to lag terribly and then crash. I opened the debug menu(F3) and saw that the memory usage got very high(100MB/s and then going back down if this makes sense). I have 2GB of memory allocated to the game which used to be enough for me to play for long periods of time. If I stay in the same chunk for a while, then memory usage goes back to a decent speed, but that doesn't stop the game from crashing eventually. I think that 1 or 2 mods added to the pack may be the cause of this issue, but I'm not certain. If anyone knows a good solution to this, please let me know, Thank you.
P.S. I did not use any texture packs at the time.