After the CCC update it no longer scans for updates after every single action. My mistake was not clicking on the orange bar at the bottom of the CCC screen to trigger a rescan of available updates. Once I did that all was good.

Something lovely and ironic in this: SONAR might get better performance with Windows 10, Cubase has "timing and performance issues" - https://www.steinberg.net/nc/en/support/knowledgebase_new/show_details/kb_show/product-compatibility-info-regarding-microsoft-windows-10.html

Start screen what are the features?

From the ezine...
 
Miscellaneous
MIDI note events with 0 length can no longer cause a crash during playback.
 
This is interesting and perhaps solves a bit of a mystery. When I first started using X3 I tried to work on a mess of a project I started in X2. There was this one tiny little MIDI clip sliver that any time playback reached that point Sonar would stop playing and if I mucked around with it it would lead to a crash. Maybe this is what was going on.

Hi all, is this update just for those who are upgrading to Windows 10?  I was planning to wait for a while before upgrading, so would the Gloucester update be wise while I am still running Windows 7?
Thanks,
Art

1. No
2. Yes, it includes updates and fixes to SONAR regardless of the Windows version running.

Had to do the "Check Now" to get the updates, even on a system with a fresh Windows 10 update. 
 
A bug in CCC?

fireberd
Had to do the "Check Now" to get the updates, even on a system with a fresh Windows 10 update. 
 
A bug in CCC?

Looks that way. Similar for me and a lot of others. Minor bug but generates a lot of forum traffic.

What hardware was this version tested on? "fully tested" is a bit bold with all due respect. 

brconflict
What hardware was this version tested on? "fully tested" is a bit bold with all due respect. 

I'm assuming it was tested by the Beta team (at least those who had the prerelease of Win10 installed) on top of the tests done in house that are detailed in the ezine (which I read this morning).
 
Pure speculation of course.