‘When running a single track of vid things are fine, nice and smooth – its when I run many tracks (3 or 4 plus) that the chugging becomes a problem, especially if the tracks have effects on. Ive just bought a Sony EX3 and the files from this cause the same prob.’
That sounds very logic to me. The more Vegas has to calculate before previewing, the more difficult preview will be. But at which point Vegas get preview problems is completely dependent on the specs of your computer.
But there is a solution to have a perfect preview under all circumstances: RAM preview or Render to new track (Ctrl M). I prefer the last one …
Theo