Do I have to re-encode?

[gdzjuba]

Hi have Canon HF100 that gives me AVCHD files on flash card.

I do not need fancy menus or transitions, I just want to group/stitch some clips together, give it some name and store them on USB drive or Blue-ray disk.

I am new to this, so maybe this is a dumb question: is re-encoding unavoidable? I have Adobe Premiere Elements 7, I know I can match output file format to my original avchd files format, but generating output takes a long time, which I conclude is because all content is decoded and then again encoded. Quality seem OK, but it's slow (I expect simple stitching should take few seconds) and I guess it has to be come loss, bacause h.264 is not loss-less.
This is as if I got mp3, convert it to wav and then back to mp3. Some fidelity will be lost. Or jpeg->tiff->jpeg. Depending on the compression rate, I can hear/see the difference.

So, my question is: is loss of data unaviodable while working with AVCHD?