"The "splash-screen" issue comes when you are running Windows 10 in a laptop that has touch screen functionality."
after installing the lastest win 10 updates, I noticed that my old install of 12.51 now starts up immediately. I no longer have to twice press Ctrl D (or whatever) to get past the splash screen. I have no idea whether related the datawindow painter paramenter issue still exists, but win10 does seem to now work much better with old PB versions.