If you work with DV, I believe that DV is usually the quickest render. Perhaps the default render would be quicker, but Magic Bullet is usually very slow.
Vasst has some good film look Tools, they work with Vegas's internal FX and thus are much quicker than MB.
They work with the big scripting tool Ultimate S or with the just film-look module called Celluoid.
Magic Bullet is its own piece of software, whereas, as busterkeaton points out, Celluloid and the ReelPaks use Vegas's own internal mechanism, for a much happier experience.
And, the ReelPaks can be used at HD resolutions, where MB will give you an error message above 1024x1024.
Just today I installed the latest version of MB Editors2. With my Nvidia 7800GTX on a dual opteron 275 using the basic look and cineform HD 29.97i I am getting 4 fps Best(Full) and 13 fps Preview(Auto) 720x540. Their new version that uses the graphics gpu rocks! Same box with version 1.1 was about 2 secs per frame......
For some of MB's effects you can duplicate them with Vegas's own FX pretty easily. I used the brightness/contrast & color corecting FX to duplicate the MB "warm" look. It looked identical on the piece of footage I was using.
But you have to play with it to get the same look & it oculd take some time. :)
VASST's Reel Paks are great and MUCH faster. MB has some nice "extras," but you pay in time. Figure conservatively on 40 minutes to an hour per finished minute of render.
The Misfire side of MB Editor's is really sweet and doesn't take nearly the time for rendering (most features, anyway). Not a lot of times you want to make use of such tools, but when you do, they really deliver the full package.
Magic Bullet is cool, especially the Misfire plugin.
However if your video is going to broadcast MB can cause some serious headaches. Just take a look at the waveform display with some of the MB filters applied. Some of them are almost impossible to correct and bring into legal range without completely destroying the look.
This why at present I always use the curves filter to get the contrast I want, along with the other built in Vegas filters. That way I can make sure the signal stays legal. I will use Misfire occasionally though, but care still needs to be taken.
One thing that Vegas really needs is a controlled black level. For example when you fade a video out it goes to blacker than black unless you cross fade to a solid colour rhat you have inserted on the timeline that is set to legal black. The broadcast filter does not help for this.