I would be interested in the two command lines so I can pick apart what parameter might have caused the performance increase.
Just got around to actually taking a look at my settings. Boy, was I wrong in saying I "just" moved it over to MultiMC...
FTB Launcher settings:
Java 1.8.0_20 64-bit
Additional java parameters: -Xms2048m -XX: PermSize=256m -XX:NewRatio=3 -XX:SurvivorRatio=3 -XX:TargetSurvivorRatio=80 -XX:MaxTenuringThreshold=8 -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:MaxGCPauseMillis=10 -XX:GCPauseIntervalMillis=50 -XX:MaxGCMinorPauseMillis=7 -XX:+ExplicitGCInvokesConcurrent -XX:+UseCMSInitiatingOccupancyOnly -XX:CMSInitiatingOccupancyFraction=60 -XX:+BindGCTaskThreadsToCPUs -Xnoclassgc
Adding Optimization Arguments: -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+CICompilerCountPerCPU -XX:+TieredCompilation
MultiMC settings:
Java 1.7.0_55 64-bit
Java Arguments:
[-Dforge.forceNoStencil=true, -XX:+UseLargePages, -XX:+AggressiveOpts, -XX:+UseFastAccessorMethods, -XX:+OptimizeStringConcat, -XX:+UseBiasedLocking, -Xincgc, -XX:MaxGCPauseMillis=10, -XX:SoftRefLRUPolicyMSPerMB=10000, -XX:+CMSParallelRemarkEnabled, -XX: ParallelGCThreads=10, -Djava.net.preferIPv4Stack=true, -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump, -Xms1024m, -Xmx3092m, -XX: PermSize=256m, -Duser.language=en, -jar, C:/Games/MultiMC/jars/NewLaunch.jar]
I thought I had gotten one of these from the Resonant Rise Google+ page, since it has the most concise list of tried-and-true settings that I could find, but I guess I didn't. Where the heck did I get these?
Edit - damn smilies...