Linux, eh? What window manager are you using? A user has discovered that some of them are shit, and not the ones you’d expect:
Read: Linux, Renoise And Choppy Sound
When you say “just on scriptable faders in renoise- all other mappings work fine” and “when turning the knob faster, the fader kind of stutters, jumps, various latencies appear between knob action and actual fader response” I can’t help but find the problems similar.
Lua scripts are run in the GUI thread…
Since you say the problem occurs on Windows too, what’s your graphic card for good measure?