Actually no.. have vegas4.

example.. taking a dv-clip adding some effects.. do a prerender.. looks ok..
.. file/render as.. .mpg file... it starts to rerender the effects.. :(

Rendering to MPEG requires the ENTIRE FILE to be rendered - not just the transitions.

exampel 2.

1.Take a dv-clip.. render to .mpeg ..lets say it took 10 seconds..
2. Add some effects.. do a prerender.. took 1minute.. then render to .mpeg, took another minute ;)
3. do as step 2, but before render to .mpeg render to a new track then render .mpeg
this time it only takes 1min to render effects and 10 sec. to do the .mpeg..

So.. why dont vegas reuse the prerenders in the first place..??

IF you do a pre render and it takes one minute, then one minute to render to MPEG. That is because it has to recreate the effect while rendering to MPEG.

If you prerender to another track and then render to MPEG, the effect is already rendered, it only has to create an MPEG, which in this case does not take much time.

Most of the CPU time is taken creating the effect.

Perhaps you are misunderstanding what prerender is actually DOING. When you take a DV, or anything else, and PRErender it to the same frame-size, you end up with DV files. Same format, same frame-size. Somethings actually get rendered, others passed over if no need to render (no changes in the clip.)

However, no matter WHAT you do, or don't do, if you tell Vegas to render AS something other than the original frame size resolution, it MUST render the whole thing. It is changing the WHOLE thing into a completely different resolution.