It’s ridiculous how much CPU speed you need to edit full 1080p AVCHD clips with Vegas. I got my hands on a 1920×1080/60i 14mbps AVCHD clip today and it plays back on the Vegas Pro timeline at ~2 fps on my P4 3Ghz (in “preview/auto” quality). Vegas only supports basic DirectDraw functions, so a faster GPU won’t help either.
Now think that the fastest affordable PC on the market is a Quad-Core Intel at 3Ghz, which is about 5 to 6 times faster than my PC (including bus/RAM speed). Now, multiply that: 6*2fps=12 fps. This means that even the fastest PC on the market today won’t give me full preview speed while editing AVCHD. I would need double that speed. And that’s before adding any plugins or transitions that slow-down preview even more.
Someone might suggest the way Apple does things: all imported footage gets re-encoded to AIC or ProRes codec before editing which are faster to edit/playback. You will have to wait for the transcoding to take place of course, and that will take quite some time for ProRes (it’s faster with AIC, but AIC is not lossless so I can’t recommend it).
So in essense, you have the choice: do you want to wait while importing in the beginning, or wanna wait while editing? In both cases, there’s gonna be stalling. This means only one thing: I will have to wait for a few more years before I decide to get an AVCHD camera and a new PC. For now, the HV20 with its faster-edited M2T format will suffice.
Update: Some people are telling me that AVCHD editing is plenty smooth on newer computers. Good to hear.