Honestly, don't use Premire for rendering. It is great for doing fancy things like transitions and audio mixing, but (in my opinion) you shouldn't use it, because there is a better, faster and FREE program to use called VirtualDub, (
www.virtualdub.org). Vdub is a nice fast and simple program to figure out, and it supplies more rock solid functionality than you will ever need. It can read in avi and MPEG-1 files, it detects all the codecs on your system and lets you reprocess and re-render in whatever codec you like, it has a large selection of filters to transform frames, and you can import your own audio in the form of a .wav file (sadly only one file though; you can get around this by editing audio in something like sound forge). It can even capture directly from devieces on your system, like premire.
I have a voodoo 3 3500 on my machine and I capture all kinds of stuff in MPEG-1 (like star trek episodes). The nice thing about Vdub is that i can load in the file, edit out 15 minutes of commercials in about 3 minutes of work, and then I choose my codec for divx and save as a new avi file. Vdub offers a slew of information while it renders, including estimated time and file size so you don't have to wait for the file to be made to realize that it will be too big or take forever to render. The whole program is assembly optimized and 320x240 DIVX renders at about 30 fps on my 800 mhz PIII with 128MB of RAM.
I do not work for the guy who made VDub, but I was very pleased the day I found this program to help me in my (albiet humble) post-processing needs. the program works, and it works well. I still haven't figured out how premire works entirely.
Oh yeah, and to answer your question, maybe you can render a finished movie in a large uncompressed format (if you have the HD space) to let premire render faster, and then reprocess the whole thing in VDub, it is worth a try.