I did a simple test of export times from CS3 and CS4. I usually export to BluRay, DVD, and iPod. So I tested these. I have listed the settings I used, but that is not as important as the relative times.
I took a 60 second 1440x1080i HDV clip and exported as follows:
CS3 to BluRay 70 Sec
CS4 to BluRay 65 Sec
CS3 to DVD 41 Sec
CS4 to DVD 44 Sec
CS3 to iPod 86 Sec
CS4 to iPod 58 Sec
I have a quad-Core2 2.83ghz, 4GB Ram, Vista x64. I read and wrote the files to the same dedicated drive.
Format.............MPEG2-DVD
Multiplexer........None
Video Size........720x480
Video Bitrate....CBR-7mb
Video Quality....4.6
Audio................PCM
Format.............MPEG2-BluRay
Multiplexer........None
Video Size........1440x1080
Video Bitrate....CBR-35mb
Video Quality....4.6
Audio................PCM
Format............H.264
Input...............Crop 4x3
Output............Scale to Fit
Multiplexer.......iPod
Video Size........640x480
Video Bitrate....VBR 1pass 1.3 to 1.5
Video Quality....N/A
Audio................AAC 128