As long as you maintain a sensible backup/versioning system this should be an unnecessary step on a modern computer.
We have a song that is virtually finished but today I decided to add a harmony hi-gain guitar line to what was already written.
Think how tedious this could get having to open different projects, un-mute/un-archive/un-freeze or whatever, then saving it down, redoing all of the above.
As CJ says - just hit E if your plugins are causing too much latency at the tracking stage.
For mixing, it matters not one bit what your latency is.