First here is the machine I have been running for about 6 months with 5 users at most on my server:
FTB Infinity: 1.9.0
any additional mods: compactmachines-1.7.10-1.20.jar
CPU model name : Intel(R) Core(TM) i7-4765T CPU @ 2.00GHz
OS: Ubuntu 14.04.2 LTS 64bit (with all current patches for os...