Hi Mark, there are a ton of reasons this can happen. I find it unlikely that your problem is related to all those photos, however. Does your site have a really large number of pages (like in the tens of thousands?), any other really large numbers you can think of here that might impact things (number of portals in the hundreds, users in the hundreds of thousands)? In the past I have run across sites with large user bases (hundreds of thousands) and a problem loading profile data for only 10 of those users at once, perhaps this is a problem on your site too (you can check the UserProfile table, if it has over a million records this could be it). 

One thing I am curious about is you are mentioning a client side expansion taking almost 30 seconds. I find this somewhat odd because it would have all been loaded in the first minute you loaded your page. Perhaps there is a problem with your skin?