I'm having a problem with lag when using the eraser brush. My composition is made up of one footage layer and one duplicate which I have modified the colours of. I am using the eraser brush on each frame of the colour corrected layer so that my subject alone shows through in its original colour.
When I started this long process (the footage is 14 seconds long at 25fps), the brush was working just fine. I'm now about a third of the way through the footage and the brush strokes are really becoming slow to respond (the stroke taking about half a second to catch up with the cursor). Pressing PGDN when I need to move on to the next frame is also becoming very slow (around four seconds).
Neither of these issues were there when I started, and both have increased in proportion to my progress. If it continues in this way, by the time I'm halfway done it will become impossible to continue. Purging makes no difference. My RAM is 4GB.
Any advice would be much appreciated, cheers.
Yes, a mundane performance issue. Simply pre-render the segments you're doen with and then start fresh with a clean slate on another segment...