Are you doing a lot of brushing and/or a lot of spot healing?
Do you have tried a clean reinstallation?
Deinstall Lightroom again.
Is your system up-to-date? If you have installed the latest graphic driver then try to install an older version. Sometime the latest drivers are buggy.
Take also a look here:
dj_paige: Yes, I do a lot of modifications in LR but this is nothing new. The slow response time is what has changed. I cannot see my adjustments as they are being made due to the not responding messages. This has even resulted in a crash at one point (crash report sent).
Axel Matt: No new graphic driver. Did a complete reinstallation. Only new thing in the last few days was an Adobe update to Camera Raw CC. But that's for Photoshop and Bridge. Couldn't have an effect here could it?
Unfortunately, if you are doing a lot of brushing and spot healing, this can slow people down, and some folks do claim that it is worse in LR 7.2. Make sure you have turned OFF the "Use Graphics Processor" box under Preferences/Performance.
Done that - thanks. Waiting for an on line chat now. Maybe they can help.
Only new thing in the last few days was an Adobe update to Camera Raw CC. But that's for Photoshop and Bridge. Couldn't have an effect here could it?
No. The CameraRaw - Update has only affected to Photoshop.
Axel Matt: No new graphic driver.
This means you have uinstalled the latest version of the graphic driver? Then try an older version.
But as fas as I read in your other answers you have made a lot of modifications to the pictures. Especially when you heavily use the brush and spot healing in Lightroom the perfomance can be extremely slow.
When you need to do many of these corrections it is better to to this in Photoshop. Make the standard development of a picture in Lightroom and the open this picture in Photoshop and make the fine tuning.
Are you syncing with the LR Mobile/Web system?
Are you doing Face Recognition?
Do you have the Address Lookup running?
Update: I was on a chat with Adobe for 3 hours this morning. They got into my machine and have been unable to find a fix yet. I'll keep you posted if they find the solution. Thanks for your help!
Final (I hope) Update:
I was out of town for a few days when Tech Support last tried to contact me. I did have my laptop with me and was still having issues but, without WIFI, I tried to set up a time to reconnect when I returned.
As soon as I returned home, I set up and waited for a call that never came. During that time, I opened LR and started working without any of the issues I had just the day before! How can that be? They did not have access to my machine and I installed no updates.
I guess I won't look a gift horse in the mouth. It's working now but I sure would like to know what went wrong so I could fix it without wasting 3+ hours.