We'd need more information on what's actually happening when it crashes. What version of the mod are you playing? What GC? What faction? What roughly is going on when it crashes (are you in tactical battles, galactic battles, any notable heroes just die)? 2.1 has no notable crashes that we're aware of if you have the patch installed, 2.2 Demo has one or two potentially related to emergent faction events that we're trying to track down. Alliance mod is not a good indicator for anything frankly, that mod is and has always been a broken pile of bugs.