Try the “Windows Defender” suggestion in this thread. Hopefully it helps (a little). 
FYI… I have maybe 20 or so older VSTs version 2.3 & 2.4 on my system. No issues with delayed start time. I have not yet done the Windows Defender idea on my Win 10 system but I did do basically the same thing with my Win 7 system and Windows Essentials and the start time improved a lot…
Regards 