This is a really old one.
1. A quick way to hear an edit without actually committing to the edit.
If you just want to cut a section of a song, but want to hear the result first.
Simply engage cycle, then set your left locator to the end of the section to be cut.
Then set your right locator to the beginning of the section to be cut.
Now playback from a point before the right locator.
The song will skip over the section enclosed in the markers.
2. Use the FXchain Presets to load whole channels at once.
(Not really a hidden/secret feature at all) I know it sounds obvious
but I haven't had to go looking for a plugin in quite some time.
I have created basic start up channels for everything...
For example: Vocal Channel - (De-esser, LA-2A, EQ)
Even FX Channels...I have 4th,8th,16th note echos in a flash.
The way over used but highly popular phone voice filter effect.
One click loads the UAD Moog Filter, LA-2A, Cambridge EQ and Precision Limiter.
Take the time to set these up and it will save you more time then you could possibly imagine.
You can designate a key command to open the fxchain preset browser as well.