A major cause for an input delay will be the audio drivers. If you’re on Windows, then you’re dealing with DirectSound instead of ASIO, so your audio latency will be much higher. Unfortunately, the demo version of Renoise doesn’t include ASIO support, so there’s no real way to make sure nothing else is adding to the delay. In Renoise’s defense, though, it’s fairly light-weight on system resources, so odds are good the delay is largely (or entirely) because of audio driver latency.
Someone running Renoise on Mac and Linux will have to cover those it you’re using either of them, though.
Although I have a paid license, I still prefer using directsound drivers in windows because asio limits the amount of app’s that can output sound at the same time, also the latency is good enough imo, but it depends on your system I guess. Either way, to the op, check out; edit/preferences/audio tab, and try lowering the latency (ms) setting until you find a sweet spot where the audio doesn’t crackle and stutter during playback/recording.