I just noticed in your earlier post you have your minimum RAM set rather high try setting the minimum to 512mb because you could be forcing it to use way more than it needs. My settings are minimum of 512mb & max of 4gb and rarely use over 1.2gb meaning it has 2.8gb spare for when it needs it.
Okay - will try that too. Can't remember where I got the min value before anyway.
Are you by chance using buildcraft fluid pipes? If so, break any wooden fluid pipes you have and see if the stuttering goes away. I had stuttering from them. It seemed to be caused by breaking the block the pipe was pulling from and then replacing the block or putting a different one there. Breaking the wooden pipe and placing it last seemed to fix the issue. Also, buildcraft fluid pipes don't seem to like mariculture tanks/crucibles. Sometimes it would be fine for a while, sometimes it would cause major log spam which would also cause stuttering. I had that problem trying to use a crucible to automate emptying buckets of lava to push the lava into an iron tank. I ended up having the crucible auto-output the lava to an adjacent buildcraft tank and then use wooden pipes to get the lava to the iron tank.
Again, thanks for the tip, but no, wasn't using the BC pipes at all yet.
On another note, @Amadeus99, your avatar and my avatar are mortal enemies!