The latest version of LR is unusable. A simple export paralyzes my laptop there or the previous version worked correctly. Thank you to fix your bugs!
While CC 2015.2.1 / 6.2.1 fixes a couple of serious bugs in 2015.2 / 6.2, there are still many reports of problems. I, and many others, recommend that you revert to CC 2015.1.1 / 6.1.1 and wait for Adobe and beta-testers to resolve all the problems. See these instructions: How do I roll back to Lightroom 2015.1.1 or Lightroom 6.1.1?