Turning off tracks
When Show Advanced Tools is selected in the Advanced preferences pane, you can turn tracks off in the Tracks area. Turning off a track lets you silence a track while still hearing other tracks in the project assigned to the same channel strip.
When no other track is assigned to the same channel strip, turning off a track also saves processing power, because plug-ins on the channel strip are no longer processed. Turning a track off (or turning it back on) takes slightly longer than muting or unmuting the track, due to internal pre-processing. Unlike muting a track, turning off a track can not be automated.
Turn off a track
Click the On/Off switch in the track header.
To turn the track on, click the On/Off switch again.