Ableton Forum

When you want to render only 1 track from say 10 tracks either by setting it to
SOLO or by chosing only this track in the Rendering Menue, Live wastes a lot of
time calculating all the other tracks aswell, eventhough they are not active and
do not appear in the rendered result.

Only when you DEACTIVATE the clips in those other tracks does LIVE only
process the content in the chosen track.

Live should know that non-selected or muted tracks needn't be considered in
the rendering process.

But Live has the renderring option to bounce only a specific track. Does also occures there?

Yes it seems so. I just tried it.
...trying it again...
unfortunately yes.
You have to deactivate all clips you don't want to be rendered if you want fast rendering.