The white flash when opening Steinberg instrument plugins on Windows has been around for awhile. I just tested Cubase 10 on Windows 8.1 and indeed this white flash when opening Steinberg instrument plugins is still present. Please see video. Anyone else?
CB Pro 10 on Win 10… no flash or even the short delay when opening with one click. I really haven’t noticed but, these annoyances seem to be fixed from previous versions. Nice. 
Regards 
That’s good to hear. C 10 plus Win 10 might be the winning combo.