Cactus Music
 I disable the Plug in scan. Why scan plug ins if you haven't installed any? 

Because it won't do anything if you haven't added/removed plugins. It only takes a second or two if nothing has changed.


If sometthing *has* changed - you actually *want* it to sscan...

Sonar is the fastest starting DAW since I disabled the automatic plugin scan and the START SCREEN!
 
And I have also installed Samplitude with the MAGIX Low Latency Driver (but I do not use this driver). It does not affact Sonar at all!

Try temporarily disabling for virus scanner.
If you are using standard hard drives (not SSD) make sure it's defragged.
Check to see if other heavy processes are running before starting Sonar using task manager or process explorer.
Process monitor is also a useful tool to see how bogged down your I/O is.

Larry Jones
UPDATE:
I disabled a bunch of nVidia HD audio drivers -- don't remember how many, at least eight -- and SONAR is starting much faster now. I now believe the Windows 1709 update caused a large part of this. Maybe I'll get around to removing the Magix Low Latency driver but so far I have not found an uninstaller for it.

I actually uninstalled (not disabled) all Nvidia software via the add/remove programs except for NVIDIA's Graphics Driver, and NVIDIA's PhysX System Software.
 
Also, if you go into the Device Manager, then click View->Show Hidden Devices, you can uninstall all of the dead linkages (they show up with an icon over them, and will reinstall themselves if ever plugged back in). When that gets messy, software is trying to connect to all of them if Windows lists them even if dead.
 
The MAGIX ASIO driver seems to be a one-off deal... it causes grief on initial load, but once configured in each program seems to behave. I was initially going to trash that, but I have a few standalone VSTis that need an ASIO driver, so it does serve a purpose.
 
The only other thing that comes to mind is there was a similar thread long ago and Noel spoke on how SONAR loads. The only time it was excessive for me was because SONAR links to available ReWire devices, and I had a flaky one. If you have installed any programs with ReWire enabled, that could also be a cause.
 
Win10 updates I cannot speak to, but I have seen folks mention issues with various updates on their machines. Often this seems that disabled settings get re-enabled each time an update occurs, so disabling things that cause issues must be done with each major update.