Thank you so much for your prompt and detailed reply. A lot of stuff makes more sense now. What you said about cpu explains a lot. I will have to give prerendering a go. That sounds like it might help.
Just to answer a couple of things. The mpeg format I was referring to was mpg and it was straight off the camera. Perhaps converting it to something else might have helped I don’t know. I use a different camera too that uses mts (avchd) and I haven’t the had the same problem with playback in vegas with that. It’s just with mpg that causes the most problems.
I can’t remember my computer’s specs off the top of my head but it has 4gb of ram and I remember saying at the time of purchase that I would be using it to edit videos (I know I was a little green back then and wasn’t quite sure what to go for). It has actually done me really well for what it is but one day in the future when I can afford it I would like to upgrade. I imagine that would make a huge difference from what you’re saying.
Thanks again for your help. Much appreciated!!