My personal rule is to have a clean boot with no services running whenever I am working with Video. This has been covered before but basically no internet, virus , spyware or anything non essential running in the background. When I render I leave the computer alone and don’t attempt to run another at the same time. I want all my CPU power and RAM to be available to the render process. You just never know when a hiccup in the process will corrupt your render so for me it is not worth the chance. As far still size is concerned, if you use high res pics then it will take a much longer time to render those files and can seem like the system is frozen. It might well be if it running out of memory. If you are done with your project then make sure you delete all unused media from the project before rendering. Vegas can work with 2meg pic files just fine but when there are many of them it really slows things down. You have to understand that you think you are adding just one pic. But if that pic is being shown for 5 seconds and also uses effects then the program must render that pic at the projects properties. For example….30FPS…(frames per second…) multiplied by 5 seconds duration that equals 150 redraws of the same pic. Now add effects and such and it does not take long to see how the resources can get used up quickly. It also is reducing the file size at the same time further slowing things down. HIDEF video does not even remotely come close to the quality of a High Res pic. The video would be huge if it could. the Try this test and see what I mean.
Take a snap shot from the Preview window set to Best Full of a high res clip. Compare the file size of that pic to the original.
Now Place that in the time line and replace it with one of the offending clips and see if it still stalls. Bet it doesn’t.
Hope this helps
Joe