v4.moatads.com site slows down complete loading of certain websites

Certain sites (not all) will load quickly but not completely (the spinning wheel continues going after most of the site has loaded). The website loads fully - and the spinning wheel stops - only after a file or site called v4.moatads.com has been incorporated into the site. I suspect this is a banner or some advertisement on the main website. The problem is I am unable to initiate printing until this v4.moatads.com file has loaded and the spinning wheel stops. An example where this happens is if I try to print a crossword puzzle on the Guardian.com website. This problem seems to have started a couple of months ago. If I use another browser (such as Safari) I don't seem to run into this problem.