Resolved. I am back to my original 5 sec shutdown on my XP SP3 machine.
What did I do?
1. I downloaded Avastclear.exe and aswclear.exe
2. Started Avastclear.exe and it asked me to restart in Safemode. Shutdown now was very fast!
3. Safemode started and Avastclear came up with Endpoint Protection (Plus) selected + path
4. Did Uninstall that + restarted in Safemode Again.
5. Did Avastclear again now uninstalled Avast Home server edition + Path
6. Did restart in safemode and now uninstalled Free/Pro/Internet security/Premier, nopath
7. Restarted in normal mode and there was no Avast present, so XP warned.
8. restarted in safemode and did aswclear.exe
9. Uninstalled version 8 and to be sure also version 7 and 6, all with nopath
10. Restarted again in normal mode and installed version 9.0.2006 again.
11. I prefer Avast with only file shield + language module installed, so no other shields and no tools.
12. Unchecked Google and Chrome stuff
13. Let the initial start scan run to the end.
13. Do all the settings you want. I prefer manual updates.
14. Shutdown now takes only 5 sec. I an relieved.
15. Restart is as fast as with no Antivirus installed. Super !
Can anyone confirm that these actions resolves your shutdown problem too?