For instant "freeze" within one channel (pre-fader):
1) insert a Melodyne Plugin after all the effects (works also on stereo channels).
2) transfer audio to the plugin (just press the button and it will auto-transfer
3) bypass the other effects in the rack, leave only Melodyne on, but do not modify any of its parameters.
4) Melodyne plays the "frozen" track for you
, and there's almost no CPU load.
5) If you save the project, all the frozen tracks are automatically saved in the Melodyne folder and they load with the project the next time you open it
And if you want to delete them, just unload this instance of Melodyne, or you can also flush them manually.
Enjoy
!