I've been incredibly lazy and have just been using makerware to slice everything at medium(standard) and high settings with the default slicers (makerware for medium, I think skeinforge for high). If you aren't using it already I would definitely recommend upgrading to the latest version of makerware (2.2.2), it does actually seem to do a much better job all around. I have also updated the machine firmware to the latest version to match.

The slicing is painfully slow at highest settings on older machines (my laptop is 8 years old and still runs MoI like a champ, but makerware not so much). On a newer machine I've found even with complex geometry that it is pretty quick. I am using Windows 7, I don't know if you are also using an XP machine for makerware?

Something like your door latch replacement would probably only take my old laptop ~1-2 minutes to slice at medium if it were say 4-5k polys. Have you tried using .obj as a format? Shouldn't make a difference, but you never know.

Also, if you haven't already definitely join the "makerbot operators forum" over on google groups. I've found it to be very useful resource for troubleshooting makerbot issues. There are tons of bugs that get through in makerbot products and the user community is often a step ahead of the company in figuring them out.

Regards,
FDP