I can confirm library load times are better now! Four open libraries just opened in about 10 seconds. Under 10.6, it would take 2-3 minutes. Woohoo! Release notes are here: support.apple.com/en-us/HT201237
For the fist time in 8 years, I didn't even take the time to update to 10.6. With all respects, let's be honest for a minute : 10.6 was certainly not a "great update". Personally, I am not really interested in tracking objects, and like many pros out there, I don't work with iPhone footage. We need so much more !
And yet, FCP still remains my favorite NLE, mostly because of the magnetic timeline.