I'm using the same shortcut I've always used for version 4, using the command argument p="".
Time was I'd double-click the desktop icon, Windower's spalsh would appear and "Launching Playonline" would appear and it was rare that it took longer than the time it takes the white dot animation to complete once before the POL Viewer would appear.
These days though the white dots can appear as many as 5 or more times, and occasionally the Viewer doesn't appear after a minute, I have to then use Task Manager to kill Windower and sometimes I'll get a cryptic error dialog from the POL Viewer even though its own dialog never appeared.
Running the Viewer directly, meaning not using Windower at all, I don't see any noticeable delay.
Is this something that is know to happen nowadays? I really can't say when it started, but the totally failure to start the Viewer I'm sure never happened before this year.