I haven't as yet tried the new version. But ways to reduce cpu use are:

1. Keep shares below 2,000 for OSX
2. Go to LW's prefs>Speed & tick disable Ultrapeer Cap. & press apply button.
3. Set both uplds & downlds to autoclear.
4. Close all LW windows you don't need open at that time.
5. If you're not in front of your comp, then hide LW in the dock. eg: Connections window.
6. Tip: Purge the Downloads Queue! (click on blue link)
7. Don't use the Resume button on all incomplete files. This can have side-fx such as affect LW's connection quality. May queue your files for much much longer. This will also stress LW & your comp. If you use Resume/Find sources then just apply it to a couple or so at one time. Better & much more effective than using these functions is -> Control-click Search tab, choose advanced from sub-menu & choose Find More Results or Search again.

* But yes, your problem might be version related.