I have just started work on an existing 2003/AD domain where users are complaining about the amount of time it takes for an XP client to reach the logon prompt after boot (around 4 minutes).
I haven't looked into this too much so far, but one thing I did notice is that there are ~150 GPOs. Most of these could be reduced by manually going through and merging several into one. It looks so far like I could achieve the same outcome with about 30 GPOs. Luckily, the GPOs are well documented.
Some wireshark traces I have done seem to show each client checking the timestamp on each file in each gpo in the sysvol share when they boot (or on a group policy refresh). This takes about 25 seconds.
I am fairly certain there are other factors that are contributing to the long boot time of the clients, but in general, is it worth keeping the number of GPOs to a minimum?