This combination works great on my Intellij13 running in Mavericks:
Updated Jul 18, 2017:
# custom IntelliJ IDEA VM options
-ea
-server
-Xms2G
-Xmx4096M
-Xss2m
-XX:MaxMetaspaceSize=2G
-XX:ReservedCodeCacheSize=1G
-XX:MetaspaceSize=512m
-XX:+UseConcMarkSweepGC
-XX:+DoEscapeAnalysis
-XX:SoftRefLRUPolicyMSPerMB=50
-XX:+UnlockExperimentalVMOptions
-Djava.net.preferIPv4Stack=true
-Dsun.io.useCanonCaches=false
-XX:LargePageSizeInBytes=256m
-XX:+UseCodeCacheFlushing
-XX:ParallelGCThreads=8
-XX:+DisableExplicitGC
-XX:+ExplicitGCInvokesConcurrent
-XX:+PrintGCDetails
-XX:+PrintFlagsFinal
-XX:+AggressiveOpts
-XX:+CMSClassUnloadingEnabled
-XX:CMSInitiatingOccupancyFraction=60
-XX:+CMSClassUnloadingEnabled
-XX:+CMSParallelRemarkEnabled
-XX:+UseAdaptiveGCBoundary
-XX:+UseSplitVerifier
-XX:CompileThreshold=10000
-XX:+OptimizeStringConcat
-XX:+UseStringCache
-XX:+UseFastAccessorMethods
-XX:+UnlockDiagnosticVMOptions
-XX:+HeapDumpOnOutOfMemoryError
-XX:+UseCompressedOops
-XX:-OmitStackTraceInFastThrow
-Dawt.useSystemAAFontSettings=lcd
-Dsun.java2d.renderer=sun.java2d.marlin.MarlinRenderingEngine
I keep this setting updated at https://github.com/adben/config/blob/master/idea64.vmoptions