Well, Avast support did provide a solution but it wasn't the one I wanted, so I kept working the problem and now I have it under control. The solution I didn't like, was to completely disable Windows defender with a registry tweak.
But what was the problem? The problem as I understand it was that windows was not booting up in an efficient orderly way. Probably aggravated by a relatively slow hdd by todays standards, and also aggravated by all the messing around I have been doing. The fix was to disable non-microsoft/non-avast/non-hardware related services and startup programs immediately after installing avast and before rebooting. This was then followed by several reboots and only renabling the services and startup programs in a couple steps but only turning on more if the previous boot was error free and the windows security icon stayed in the system tray. I believe this helped windows get the startup sequence and prefetch stuff straightened out. Took awhile but Im happy now.
I did try the beta version yesterday but it wasn't working for me.
I used to use a nifty boot optimizer command along with windows 7 ADK, it would do all this automagically. One of these days I'm going to figure out how to do that on Win10.