Wow, didn't know Fastclick is still in operation. I thought they were already bought by Valueclick. Definitely, remove Fastclick first and test ad load for a few days. If it improves, then you know the culprit that's causing the slow load.

ad network that sends ads out to multiple providers (including Adsense), and returns the highest bid

Which one?

There are several that do this and they will all tell you there code doesn't slow down page load. IMO they all do to some extent. Whatever you do don't put an ad from one of these networks so it loads first on your page, like in the header, or before your main content. If it hangs my experience has been the entire page will hang while they complete their "real-time bidding process".

There are several that do this and they will all tell you there code doesn't slow down page load. IMO they all do to some extent. Whatever you do don't put an ad from one of these networks so it loads first on your page, like in the header, or before your main content. If it hangs my experience has been the entire page will hang while they complete their "real-time bidding process".

What did you ad platform provider say about the issue?

30 seconds to load an ad (ad document complete) could very well have a significant impact on your revenue and possibly your search rankings.

You may want to experiment using a different ad platform or just running adsense and see if you earn more.

The ad platform I'm using is a little more specialized for my industry, and it's in the contract that I'm not supposed to publicize our relationship without approval, so I won't mention their name. They're small enough that you probably haven't heard of them, anyway.

The reason I changed was because RPM with Adsense had been going down for the last several months. When I switched (in April), the RPM went from $1.02 to about $1.80, which was awesome, but over time I noticed that the site traffic was going down.

At first, it was negligible, but every day it was a little lower. Comparing Aug 1-24 to Mar 1-24, I'm seeing a 26% drop in pageviews (which is about 700k pageviews). At $1.80 ROM, that translates to a potential loss of $1,260.

Or, if you prefer, I'm seeing a 19% drop when comparing Aug 1-24, 2013 to Aug 1-24, 2012 (about 600k pageviews). Comparing March 2013 to March 2012, we saw a 1.5% increase in pageviews, so a negative difference is definitely not something we're used to seeing. When comparing YTD 2013 vs. YTD 2012, the difference clearly begins at the end of April.

Regardless, though, I suspect now that the slow responder was having a negative impact on search engine placement, which would explain the almost immediate loss of pageviews. Both unique visitors and pages per visit went down, and both can be explained by ranking and slow pages (making visitors leave earlier than usual).

I emailed my rep, and his tech team agreed and tentatively removed Fastclick from the network list. They're supposed to meet with Fastclick on Monday and discuss the problem. It's too soon to tell if that made much of a difference, but I'll be keeping my eye on it.

Thanks for all of the advice!

Wow, didn't know Fastclick is still in operation

Fastclick was acquired by ValueClick way back in 2005, but ads may still be served from the fastclick.net domain.