New world? Probably chunk generation.
If you are running into this issue in areas where you are generating new chunks, I've found that both COG and UB are pains in 164 when they were very nice and happy in 152.
If you are not generating new chunks, then it's a little less clear.
Does it happen both when you are a single player game, and when you connect to an SMP server on the local machine? An SMP server won't pause the tick speed for client rendering issues, so if it happens in one and not the other, that's something to look for. (If it happens in single player only, it may be rendering; if it happens in SMP only, it's in the tick handling side.)
Beyond that, something that causes tick spikes sometimes in mods, but not vanilla? Very possibly the garbage collection. Try adding -XX:+UseConcMarkSweepGC and see if there are any improvements. But really, without some baselevel comparisons, that's not of much use unless "it just works" -- for that, you need to read logs.
-XX:+PrintGCDateStamps -XX:+PrintHeapAtGC -XX:+PrintTenuringDistribution -XX:+PrintGCDetails -Xloggc:GC.log
That gives the garbage collection details, with time stamp; this lets you read the logs, look for garbage collection operations that take a long time, and see if those match up with your "This is laggy now" observations.
Yes, it can be a pain, but it's the only way I know of to determine if it is a garbage collection issue. Eyamaz has far more information and experience adjusting compiler settings than I do.
If you are running into this issue in areas where you are generating new chunks, I've found that both COG and UB are pains in 164 when they were very nice and happy in 152.
If you are not generating new chunks, then it's a little less clear.
Does it happen both when you are a single player game, and when you connect to an SMP server on the local machine? An SMP server won't pause the tick speed for client rendering issues, so if it happens in one and not the other, that's something to look for. (If it happens in single player only, it may be rendering; if it happens in SMP only, it's in the tick handling side.)
Beyond that, something that causes tick spikes sometimes in mods, but not vanilla? Very possibly the garbage collection. Try adding -XX:+UseConcMarkSweepGC and see if there are any improvements. But really, without some baselevel comparisons, that's not of much use unless "it just works" -- for that, you need to read logs.
-XX:+PrintGCDateStamps -XX:+PrintHeapAtGC -XX:+PrintTenuringDistribution -XX:+PrintGCDetails -Xloggc:GC.log
That gives the garbage collection details, with time stamp; this lets you read the logs, look for garbage collection operations that take a long time, and see if those match up with your "This is laggy now" observations.
Yes, it can be a pain, but it's the only way I know of to determine if it is a garbage collection issue. Eyamaz has far more information and experience adjusting compiler settings than I do.