That's a similar problem as OSX users (such as myself) were having with LW 4.10.0

Close off old search tabs can partially help. I believe it's a Java bug. Or certainly is in mac osx. I found LW 4.12 to be less of an issue in this regard.

BTW keeping shares less than 2,000 & occasionally purging your incompletes can greatly help; Tip: Purge the Downloads Queue!

Also try setting up a virgin account on your computer. Install LW & see if it has same problems.

Also be wary of using the Resume/Find Sources function on all your files at one time. Instead just apply to a few at a time if you use that function.

Not being a windows expert, see if you can increase the Virtual Memory.