Help! Slow Battery Discharge

You really don't have to guess, here. I doubt very much that it's the fuel pump, unless it's wired pretty weird.

Read the thread, use a meter and a test light as suggested. IT IS IMPORTANT to start with a test light, because it is very much POSSIBLE that if you have a large draw, you might pop the current fuse in your meter. What happens "when that happens" is you look at the meter and it reads zero, and you think, "I have not draw" when in fact the meter is not working!!

I know nothing about Optima batteries, but if they are that unreliable, I'd say it's money wasted.