Try a
SAFE Boot & Repair Permissions Also delete some of your older incompletes (if you have any older ones) that are 0%. You should do this in both the downld window (click the top of Status bar to arrange with 0% at top or bottom of list), & also th incomplete folder (easiest when LW is closed & arrange the folder by size.) This should help to reduce some of the stress on LW. Also set your downlds for autocomplete & close all windows you're not using. Also hide LW in the dock when you're not in front of comp.