Ableton’s compressor, filter and gate supports sidechaining. It is a great feature, when you are looking for a more cohesive mix, fixing mixing issues or just looking for interesting sound effects. Especially when you work with products from Native Instruments you get a too high CPU load and as you probably know, that does compromise the timing of your DAW. Unfortunally Ableton don’t allow to freeze the tracks, which are used for sidechaining.
And here is a simple workaround. Maybe you like to control a filter by a drum beat, in order to modulate the sound of a synth. First of all listen to the drums and synth without sidechaining.
I added an Auto Filter to the synth track and enabled sidechaining from the drum track.
It sounds as expected – the drums do contol the filter:
And here is the problem: When you try to freeze one of the tracks, Ableton reject this with the message, that the track “cannot be frozen because of the routing”.
My workaround depends on Ableton’s routing. I create two new audio tracks and rout the audio from the old tracks to the new tracks by changing the Audio To in the In/Out Section. Know you have to switch the Monitoring of the new tracks to In, otherwise you will hear nothing. And the last two step are moving the Auto Filter to the corresponding new audio track and set the Audio From to the appropriate new audio track.
That’s all! Now you can freeze the old audio tracks and just the filter will calculated in real time. Personally, I prefer using groups instead of new audio tracks, because this approach is simpler and keeps the clarity.
I hope that’s help. alexander
hear and know 
nice technique! i was doing it way more complicated ^^
I really like your picture diagrams – It was exactly what I was looking for!