Try updating to the latest version. I believe there was some improvements for mac version.
769 MB of what? The figure doesn't seem to add up. If it's ram then you've calculated incorrectly by the looks.
Try not using the resume function on too many files. It's much more efficient & healthier for LW to do manual searches.
By the way here's some hints:
A well set-up LW can start to automatically continue its dwnlding after it's settled down perhaps 2 out of 3 times you open LW. Optimising LW & Maximising Uplds & Dwnlds A (1st post only) & also Part B which is even better & last & least are search & dwnld hints. The latter one I've been thinking about re-writing for some time. That's just for playing it safe. eg- I show all speeds & qualities.