OS X unusably unresponsive after upgrading 10.6 to 10.8 Every other click and keystroke seems to cause my MacBook to just freeze for minutes at a time.

(I saw How to fix OS X Lion being unresponsive? but I'm not seeing much swap activity nor is my RAM filled up, according to the Activity Monitor.)

At this point I'd just like to salvage my data off the machine so I can do a clean reinstall, which hopefully will address the problem.  But it's taking forever to do anything, even bring up a menu/Finder or type in "terminal."

I guess my questions boil down to:


Ideally, is there a service/process/etc. that I should disable/stop/kill?  (If I can even get to it....)  I don't see any processes consuming much CPU/RAM, so I have no candidates to kill.  Is there a service that I should be disabling?  I'm new to OS X so I'm not sure how to debug this issue.
Otherwise, is there any way for me to at least get a "bare minimum" system up so that I can copy my files off, and perhaps run a few applications so as to export certain data that aren't neatly available for copying off as files?  Should I be rescuing via a live CD (which means I won't be able to run OS X applications to export data but if that's the only option then so be it)?  What would be a good live CD for this - Ubuntu?


Thanks.
Ultimately I discovered that there exists a Safe Mode, which you can access by pressing and holding Shift after the gray boot screen appears. In this mode the system was responsive again, and I could actually copy my data off.

There also exists a more restrictive Recovery Mode, which you can access by pressing and holding Command+R, and you can use Disk Utility there to copy entire disks around. However, that wasn't necessary for me (until it came time to wipe out and reinstall the OS).