if using some vst-effects or especially when using the dx-vst wrapper with renoise, there is often a lag. especially for drums even a small lag gets annoying.
now the idea is to do a “sync” button to compensate that lag.
technically it could be done by just sending a small click at the channel with the effects and internally (means in renoise) measuring the time the click takes to go through the chain of effects. then play the track ahead so that its back in sync to the master speed. (If I remember right there was something like that in Cubase VST).
would be very useful, because some effects are not usable in renoise because of this lag.