Does anyone have a clue why the reverb sometimes gets cut long before it has faded out? It seems to happen when using several instances on several tracks (I’m often too lazy to use sendtracks). Are the reverbs maybe limited to 4 instances since the Noisetrekker era?
hm, what about trying a different reverb, then?
Sometimes somethings like these apear if the grafics card can´t handle the dos gui of renoise. Try bouncing the track and playing the *.wav in order to get to know if it’s just a matter of live playing. When the bounced file sound okay and the reverb sounds like it should, it’s surely only a matter of live playing.
Finally after 2 months I managed to reproduce this annoying bug! 
It’s not a matter of how many reverbs I use cause I removed all but one. And now I’ve bought a new computer so it’s not a specific hardware problem. It seems to occur more frequently or faster when using a low sample volume. I’ll send more details and examples to the renoise bug mail…
This bug has been reported fixed by taktik now… (not that anyone else but me ever had the problem)…
Johan, actually, I did. I have several rendered songs where this effect is very audible. I didn’t know how to actually reproduce it though, good thing it’s fixed. 
I found out that increasing the processing buffer size partially fixed the problem. I.e. it worked better in a few songs, but when stuffing in more notes, instruments and fx the problem arised again 
This might be a workaround for now until the next Renoise version.