Optimising render times is something I specialise in, but I’d need you to send me the source to figure it out. If it is under 10mb you could email it to me. You might be doing it already by the best method, but without picking your scene apart it would take a long Q and A to get to the bottom of it.
Thanks for taking a look I’ve pmed you a link where you can download the scene. It is 12MB and zipping the file didn’t make a difference in size.
No problem, I’m rendering a video as a response, I’ll post it up on youtube unlisted (hidden) and pass you a link in a pm when it is done. If you want your modified source file back I can email it to you via yousendit - I just need your email address.