Complex warping causes problems

[Sugglew]

I'm using ableton live to tidy recorded instruments. I have 4 drum tracks, 2 piano, 2 guitar and some others.
They are all on separate tracks in ableton and all the clips are the same length. I've warped the drum clips together and the pianos with the guitar clips. The piano and guitar parts are playing for 41 bars before the drums clips have audio in them.

When I finished warping I had some artefacts and found that complex warping was best for clearing them with all the clips but when I select complex on the drum clips the first 41 bars of the guitar and piano tracks become a strange kind of digital garble. They sound time stretched many times more than what they are. Once the drums kick in everything is clean again, but before that, noise. If I switch the drum clips to any other warp mode it's clean and if I trim the drum clips to start at 41 bars instead of silence playing on that clip it's also fine.

I want to understand what's happening here in case trimming the drum clips just postpones a problem that will return later.

Any thoughts?



Update: End of a very long day yesterday and I omitted to mention some obvious things. The CPU usage jumps to 200% when this distortion occurs. It just makes it more a mystery to me that everything comes right when the drums come in. I've turned off all effects and it still happens.