Same here, i also get lag of fps after 10~min or so, the cpu goes up.Not sure where to post this but; I was wondering if anyone has had issues with lag or lock ups? I've barely gotten anywhere in the pack, just manually mining and building up resources but after a short time of my world running I start getting random lock ups. It seems like my fps drops from 130+ to 0 then goes back to normal. They become more frequent and last longer as time goes on. When it became really bad this last time around I took a look at my CPU usage and it just shoots up from around 30% to 90% or higher then goes right back done a second or two later. Version 1.20 of the game. Windows 7, Nvidia GeForce 960, Intel i5 3.30 Ghz, 16 GB RAM. (if any of that helps).
Edit: I wanted to add that exiting my world, not closing minecraft, but just exiting to the menu makes the sky rocketing CPU usage go back to normal. Once I get back in the game and some time passes it starts up again.
windows 10 pro x64, fx8150 @3.6ghz, gtx660 16gb ram.
java arguments :"-Xmx6G -Xms512M -Xmn768m -XX:+DisableExplicitGC -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:+UseNUMA -XX:+CMSParallelRemarkEnabled -XX:MaxTenuringThreshold=15 -XX:MaxGCPauseMillis=30 -XX:GCPauseIntervalMillis=150 -XX:+UseAdaptiveGCBoundary -XX:-UseGCOverheadLimit -XX:+UseBiasedLocking -XX:SurvivorRatio=8 -XX:TargetSurvivorRatio=90 -XX:MaxTenuringThreshold=15 -Dfml.ignorePatchDiscrepancies=true -Dfml.ignoreInvalidMinecraftCertificates=true -XX:+UseFastAccessorMethods -XX:+UseCompressedOops -XX:+OptimizeStringConcat -XX:+AggressiveOpts -XX:ReservedCodeCacheSize=2048m -XX:+UseCodeCacheFlushing -XX:SoftRefLRUPolicyMSPerMB=10000 -XX: ParallelGCThreads=8"