Ctrl-X in sample ed. with long sample and undo takes a while

If I load some long sample (stereo 44,1 wav, 340 secs) and cut some parts out from it using Ctrl+X, Renoise makes a long pause on every cut while I can read “Generating undo data” in statusbar. After there is written “Done.”, the greatly feared beachball also appears for maybe one second. Altogether every cut takes about 4-5 seconds of delay.

Seems to be related to “undo” option.

I doubt that. When you uncheck the “Undo” checkbox on the lower left, does it then cut the part faster?
Renoise has to save the complete current state of the sample to an undo buffer folder and trust me:it won’t write down a 340ms mp3 to the undo folder but a big fat uncompressed 32-bit .WAV file because mp3/ogg/flac files are always decoded to memory in full 32-bit float WAV format.

vV you are right, while disabled undo, the cuts have no delay anymore at all. So the undo could be optimized, maybe saving only the cut parts? Also the beachball indicates that the process becomes unresponsive.

Try rearranging a hour-long liveset in the sample editor. Just turn undo off for a second, and make no mistakes!!
I try to work around it with either the undo unchecked, or use ctrl-shift-alt-c if I can.

That kind of undo is even scriptable. (cutting out the selection, save it to disk with the sampleposition and undo-orderstep).