From my experience, I think you can speed up by choosing which clues you deal with first, rather than simply going through the list.
I choose to complete the clues in the following order:
1. The 5 people are - this always gives you 9 X's on your grid, so dealing with this first makes that clear.
2. The Positive clues - eg Polly drinks cola
3. The Negative clues - eg Polly does not drink cola
4. The remaining clues
Hope that helps