Can you check in console (just type console in the magnifying glass in the menu bar) for Lightroom crash reports in the user diagnostic reports section? Show us what it says in the most recent file.
Are you running any special utilities? antivirus, extra firewalls, etc?
Try seeing if turning off "graphic card acceleration" in Preferences->performance helps (I assume you are using LR 6/CC)
Thank you the second part seemed to help
Please ignore spelling by Siri