LOGON SPEED : GPO settings vs script reg import etc

Hi all - I'm preparing a new system of pcs/server and I'm trying to speed up the login time at all costs as it's the biggest problem for waiting users with restricted logon periods. I'm thinking of using mandatory profiles rather than have them generate profiles from the default user every time they logon (it's a library environment so profiles aren't stored and should all be the same). I've got all settings and stuff I need in GPOs - but I'm wondering if it would be faster to do what I used to do and have a machine startup script that runs a reg file with all the HKLM modifications the PC needs on startup (before users are waiting at logon). I guess the computer GPOs apply at that point also so no difference to the user logon time. But I'm just keen to get as few physical GPOs as possible and I guess as few settings in each one since I know they will get applied every time at logon and I'm led to believe GPOs are usually the longest delay at a logon? I've not turned verbose logons on yet and measured the login time but I may try this (I hope verbose will display more than 'please wait' and show me the GPO name it's processing or something - else I may have to delve into logging again /shiver)

Any thoughts on this or general ways to get the minimum user logon time in fixed lab environment welcome! Been a while since I had to sort this

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Leozack