Last week I was having a discussion with a colleague (@LupoLoopy) regarding Group Policy processing times and the ago old question of do you create a small handful of behemoth GPOs, or do you create lots of small targetted GPOs for specific purposes?
In this iteration of the debate, I was on the side of small and targetted and my colleague was on the side of the behemoth.
After the discussion, I did a bit of online digging, and turned up a post on the TechNet Magazine at Microsoft by Darren Mar-Elia, a Group Policy MVP. The outcome of the article is that, in his opinion, and based on research by using User Environment timers for monitoring the processing of Group Policy objects, small and targetted seems to be the best strategy.
When a GPO is updated with a change by an administrator, the client will have to process all of the settings within the GPO to determine which settings have changed and determine which settings it needs to apply, however in small and tightly targetted GPOs, there are much fewer settings per GPO which means even in a high churn Active Directory environment, fewer client-side settings need to be re-evaluated.
In largely static environments where there is a very low rate of churn, it could be entirely suitable to use fewer larger GPOs to apply larger configuration setts in bulk, however this will depend on the environment, and following the advice in the link below will allow you to determine the best scenario for your environment.
For anyone interested in reading the full article, you can see it at http://technet.microsoft.com/en-us/magazine/2008.01.gpperf.aspx.