Small intermitent "micro" lag

Try playing around with GC Rate and Time Mult. Try with Smooth Buffer on and off, too. HTH

Thanks both for the suggestions, couldn't check yet.

For clarity what I do get (would probably be correct to call it stuttering) is loose of smoothness for couple of seconds. Example: if I constantly zoom in an zoom out for a while the movement is at first smooth, but then for couple of seconds I see the image "jumping", like it is skipping a couple of frames, then it goes back to smooth. I notice this happens even at game start so that should make some culprits less probable (but the memory allocations related ideas that you point out could make sense).

None of the things seemed to solve it or have a noticeable impact.

I tried to further isolate it (for example disabled many effects widgets and anything that did not sound useful) and it happens even with a single player game (so only local) when game is paused (which should eliminate a bunch of things).

I activated the "Frame Grapher" plugin (hope the plugin is still relevant). What I notice: after starting the game (single player with easy bot) I get between 5 and 10 seconds of "very tall red bars displayed" (which I interpret as much lower than 60fps) followed by 5 to 10 seconds of "very small green bars",

The strangest part is that sometimes after an unknown amount of time, I see only green. Like after 15 minutes (after I built some units, did stuff, etc.).

I did not see anything different in infolog.txt between the two modes.

Any suggestions to further debug this?

Sorry, this is a shot in the dark, I know, but I've had a similar problem in the past (not with ZK though) and the culprit was my AV blocking and scanning a USB device which should not have had anything to do with the game I was trying to play... go figure! This was on Windows and I never encountered anything like that in Linux, so YMMV, but as a last resort, may want to remove your AV and any extra peripherals just to be sure.