Having worked with the freeze functions in a few apps, i feel they all kind of fall short in terms of time saving workflow. any time you want to change the arrangement of a frozen sequence or region or clip, you have to unfreeze and re-freeze anyway. I feel the freeze function has been added to apps as a marketing tool to keep up with the feature sets of competing apps.
I would propose someting along the lines of digidesign's "deactivate track" feature which has been in protools since OS9. with this feature, a track with all of it's associated plugins/instruments are completely deactivated (as opposed to bypassed) freeing up CPU. It's like turning off plugins but better because i've found that bypassing or 'turning off" plugs doesn't always reclaim CPU. Deactivation is like deleting the plug or track altogether, but all the settings are retained if you want to reactivate. It's not as elegant as a 1 button freeze but more useful IMHO.
Here's how it works. Let's say I have a VSTi and some plugins on an aux track (in Live's case a Midi track)and a 4 bar midi sequence. I want to free up some CPU so I'll route that track to a new audio track and record the sequence to audio. I then deactivate the track freeing up processor cycles and I'm able to manipulate the audio freely. If I want to change the sequence or automate, let's say a filter sweep, at a certain point in the arrangement, I just re-activate the vsti track, record my new clip or automation where I want it, dump the result to my audio track in the arrangement and deactivate the track again. The beauty of this is the user can render what ever they want without having to re-render an entire track. if you just want to change a small piece you can. Another adavantage to this is if, upon reactivating a deactivated track, the user is spiking the CPU they can deactivate other tracks to free CPU without having to render new audio tracks. Also in ProTools, when you re-open a session with some deactivated tracks, they will reactivate with all settings and patches intact (unless a sample library was moved/deleted or some other bonehead move)
It's basically the same as a freeze function but it's not automated. The user has much more control over what goes on.
I'm probably the only fan of digidesign's software ergonomics and engineering on this site (though I hate their buisness practices). I have to say, in terms of operation, Protools is very streamlined. they may not be the best at everything (midi editing is still pretty bad, but it's better than 2 years ago) but when it comes to manipulating audio they're pretty damn good. I get more done in Live and i love it as creative vehicle but a good part of my income comes from knowing how to use protools.
that's my 2 cents. i welcome any comments, questions, criticisms and convictions and, no, i didn't use spellcheck.
:edit:
one thing i forgot to mention, you can hide tracks in protools as well. So when you deactivate a track you can hide it and it's associated midi track so they don't take up screen real estate. sometimes i would have 30 tracks deactivated and hidden. if i wanted to tweek one part I would just show and re-activate that one track and make my changes. it also works great for doing submixes. if you submix a group of vocals to a single stereo track you can just de-activate and hide the individual vox tracks after bouncing them saving CPU and getting those tracks out of the way. if you want to make changes down the line you can just show and re-activate those tracks along with all their associated plugins, routings and settings intact and make adjuctments as necessary.
