Ghostery, the browser plugin that allows its users to "track the trackers," just released data on the tags, widgets and analytics on websites that are the worst in terms of slowing page loads to a crawl.
Update: Ghostery discovered an error in their original data set. It appears that Millenial Media was not on this year's list at all, and the #2 slot belonged to AdFunky. Both the text and the graph above have been changed to reflect this.
Any webmaster worth his or her salt already knows that slow page loads adversely affect Google rank and pageviews, but not everyone seems to have gotten the memo.
Ghostery estimates that if you put all of the top 10 worst "lagtags" on a single website, it would add 22 seconds to its load time.
And while the worst offender on the list, "Avalanchers" appears to be a fairly spammy link-sharing network, number two on the list, Millenial Media, appears to be a reputable "mobile advertising network" with a long list of top-tier clients, including Warner Brothers, McDonald's, and Chrysler.
Targeted advertising firm AdFusion also made the list, slowing page load times by nearly two seconds. (An eternity in user-perceived web time.)
Rounding out the rogue's gallery of laggy tags, hosting provider to the masses GoDaddy will charge you $3 a month to slow down your site with its Analytics package. I believe P.T. Barnum had a thing or two to say about that.
Source : http://www.technologyreview.in/blog/mimssbits/27371/