Hey I recently noticed very strange behavior of specific code. It seems to be Firefox specific, and hard to debug. I prepared set of demo pages. All of these demos work properly in Chrome and there are some issues in Firefox. Example 1 loads the ads after clicking on the button, instead of loading them immediately. Only one of those two method works in Firefox. Example 2 loads the ad immediately using postscribe, what works fine in all browsers, even Firefox. The same code works fine if called immediately, doesn't work if called after some delay (even if 100ms). The ad loading implementation has two steps: 1. Loading main script with all ad slots definitions and with googletag main script 2. Loading single ad slots scripts, they are rather simply - googletag.display() call mainly See the example: http://jsfiddle.net/5xunxpmL/ This one calls postscribe immediately (exactly the same method like previously, but without any timeout): http://jsfiddle.net/5xunxpmL/1/ Could you please check if you can observe the same issue in Firefox? The actual ad request is getting aborted in Firefox for some reason, and the creative is never fetched. GET ads?gdfp_req=1&correlato...588686&ga_hid=772171976 Aborted I can't see anything wrong with the code. I would appreciate any help.