First:

I can't seem to reproduce the problem as I am trying it.

What settings are you using on the plug-in?
What type of file is being read on the track that has the problem? (Format, bit-depth, sample rate, etc)
What is the type of file you are rendering?

Second:

The Sonic Foundry Pitch Shifter isn’t the best choice anyway, especially considering the built in event stretching uses exactly the same algorithm (which is more optimized in Vegas)! Try holding down CTRL and dragging an event edge sometime! Also try right-clicking on an event and selecting the “Properties…” item. Switch to any “time stretch/pitch shift” mode and have fun with the parameters! Also note that for the “Change Pitch, Preserve Length” option, the “Crossfade” setting should look very familiar to what you have in the Pitch Shift plug-in’s mode setting.

Third:

Any plug-in that takes in more or less data than it reads in (over the long run) is going to pose other temporal problems when used in Vegas, and always will. Pitch shift is one good example. That's why we put the pitch shift into vegas at the event level!

The event stretching/pitch changing is the number one cause of clicks and pops and glitches and skipiness for me in vegas 4

SonicMattL

I'm using 24bit 44.1k wave files and the pitch shift settings are as follows.

shifted down anywhere between 50 and 100 cents
any of the voice programs
preserve duration checked

I hadn't used the per event solution as I'm doing a lot of children's
books on cassette and these voice tracks have a large number
of events. If it's optimised for Vegas I'll give it a shot your way
and see how it comes out. I suppose I could select all the events
and drag the edge of one so that they all receive the same amount
of pitch shift.

Thanks for the response.

Dave

Yes, there's an issue with the time stretch (both in the plug-in and built-in to vegas). It likes to consume a lot of data right at the get-go and periodically rather than consuming data consistently. This results in gapping every time the processing time of a big gulp exceeds that allotted by the audio driver.

Solution: If you can, go to larger latency settings. If not, and you can stand it, select a lower quality resample like "preview" ("best" is a real cpu suck and will compound time stretch’s gulping problem) - just remember to set this back to "best" before rendering.