I have an AVCHD cam, which I mostly use baby clips. As such I end up with a bunch of clips from the "same moment" with only part of the material being useful. I got the PE7 trial hoping to have the following workflow:
1) Screen the clips and discard bad ones
2) Trim the rest, add title screen, transitions, and combine them into one clip of the moment
3) Save in clip AVCHD for the day I'll have HD playback possibility
4) Save a low-res DivX clip for playback in laptops and DVD-players
5) Include low-res clip in PSE albums and upload to Photoshop.com
It's painfully obvious that in PE7 1) is a bit difficult because of performance (other AVCHD codecs seem to perform better), and 3) & 4) are not supported. The latter I can go around by re-encoding to DivX, but 3) is problematic. I guess my options are:
a) Leave clips as is and just save the project (and worry about making HD disks later).
b) Convert the HD clip to H264. Conversion takes about 10x of the clip length in my machine, and takes almost 2x space compared to the original AVCHD, so it's less than optimal. Any experience on how the quality of the PE transcoder is? Also, if I'd later create Blueray disks of those, do I need to again transcode or can PE use them 'as-is'?
c) Get some other software. I like the PSE interface for photos, and was looking forward to using photoshop.com, but with issues in PE and photoshop.com restricted to US, it seems like a hassle :(
Without more information on your system (you don't say what operating system you're using, what type of processor you have, how much RAM you have or even if you're using a desktop or a laptop), it's hard to comment except to say that it sounds like you're pretty unhappy with the workflow.
If I were you, I'd definitely consider other editing software -- although it takes a LOT of power to handle and edit and AVCHD video, so unless your computer is up to spec, I'm not sure you're going to see much peppier performance.