It's a Catch 22. The administrators have upgraded the sofware, increased load capacity, etc., many times. But, at peak times, when thousands of people are on the discussion boards, using search significantly decreases posting time on the boards. There are too many people who are affected when trying to post questions, etc., during these times, so in trying out different ways to increase the speed, they found that by using a system that automatically disables search when a certain load is reached, less people are affected adversely. Believe me, it's worse when you can't even get on the boards because so many people are using them.
Like others, I either get on early in the morning or late afternoon/evening to do my searches.