UPDATE with 4.5.2 Beta II code base.
WOW! The refresh speed is incredible. Running on my Core2Duo with Windows XP Pro, 2GB RAM, and 2x 160Gb hard drives in RAID 0 (striped) mode results in a refresh speed of 6:30, down from 18:20 with 3392 images. The image processing phase lasts just SEVEN SECONDS!!! The rest of the time is HTML file generation. WOW. Tighten the seatbelts!
Now the bad news. Where the original post pointed out that a full refresh (not reusing existing images) could be completed in 33:04 (again, the same directory of 3392 images), the original split was 31:00 in image generation and 2:04 in HTML file generation. With Beta II, the image generation time dropped to 27:55, but the HTML generation added 6 minutes to bring total generation time to 33:54. Overall speed is comparable between Beta I and Beta II, but whatever performance improvements were implemented in the JPG generation was eaten up by the change in HTML generation which now appears consistent between both full generation and reuse image modes at around 6.5 minutes.
From a severity level for this issue, I would lower this now since I don't do full refreshes all the time and have a workaround since I personally do incremental updates more often than full refreshes and the speed improvement in the incremental update (reuse images mode) is very welcome. Anything you could do to find why Beta I had faster HTML generation and bring that to Beta II in a future enhancement release would be greatly appreciated.
-Mike