Woo, gotcha. But seriously, don't fanny around in endless debug cycles that take an hour a shot. Where you can, make sure that your debug iterations are fast so that you don't lose your train of thought about the debugging. This can mean that you will want to optimise your code or data before it works. As long as it is a simple to understand optimisation, then you're probably better off with it than without it.
I'm sure some people will argue with this, but my point is this: If you spend ages waiting to get to the moment that you can debug, you might only get to it 10-20 times a day, but if you optimise the code a little, especially if it's an approach optimisation, you might get to look at the same bug 100-200 times.
My caveat then is don't ever make silly little optimisations that get you back 10-20%, attempt very large ones that you know should make an order of magnitude difference.