Your licensing model is still on perpetual (LR 6) and not on subscription (CC 2015).
However, this does not have any influence on the performance, but you will miss out on the CC features.
Please update the Nvidia graphic card driver to the latest version and see if this helps: http://www.nvidia.com/download/driverResults.aspx/113448/en-us
Yes, I noticed the licensing model too, but the splash screen and about... both show 2015.8
I'll get back about the driver later.
After receiving your advice on updating the graphics card driver everything was working very sweetly so I didn't update it (if it ain't broke, don't fix it) until this evening when...
- LR CC 2015.8 had been running for 3 or 4 hours
- I moved 16 photos into the LR Watched Folder.
- Just 2 were automatically imported to my Newly Imported folder, but not renamed as they should have been and neither are they in the catalog, then the Import button was greyed-out.
- I uninstalled LR CC 2015.8 and installed 2015.0 then updated to 2015.7
- LR, when started, correctly imported the remaining files (and the original 2 once I'd moved them back to the Watched Folder).
- After several minutes work in the Library, Develop and Book modules it suddenly slowed down as per my original problem above.
I have now rebooted in order to update this post and will then update the graphics card driver.