The FAQ section has information on visas including the EEA2.

I believe they ultimately need to reply within 6 months from the time they receive the application, but the COA should arrive much quicker, it seems most people receive it in about a month.

Anyone sent an application recently? Have you received your permit etc?

 

Home Office will process your application and give you the COA on or before the 6 month period, as this is clearly outlined in the EU Directive.

In my past experience since coming here in 2005, it has been longer before but recent applications have taken on average about 3 months. Assuming all your paperwork with the application is correct and complete, then you shouldn't have to worry about anything, but I do agree the waiting can be a pain.