I run a server and play on the same machine. In tekkit 1.0.6 I had 4 gigs to the server and 1 allocated to me. Ran fine. When I updated to 1.1.8 I had to right a startup command script to get get the launcher to keep from crashing to run JAVA 1.6 instead of 1.7. I also clicked the increase permagemsize option. I can load the game on the SMP server but the game is not playable for all the lag. I have tried every graphics setting possible to lighten the load. my server window says the server is using minimal memory and my activity monitor says I have plenty of RAM. Again, this worked fine in 1.0.6