londrum - 9:23 pm on Jan 17, 2010 (gmt 0)
i used to work for a travel company and they had to pull the availability and prices from the airlines for each individual quote. airlines charge travel companies different rates for the seats depending on how many are remaining on the flight -- even if they are all in the same class. so economy seats might have ten different prices. and travel companies can't know know how many seats are remaining on each flight until they ask the airline. so even if the travel company keeps the price the same to the customer, they still have to get the changing info from the airline so they know how much they are paying.
and when you think that a page might contain flight quotes for 5 different airlines, that adds up to a lot of waiting