Internet Explorer network developer tools long Gap time

Question

I'm optimizing a webpage. The page takes about 5 seconds to load in Chrome, but 15 seconds in IE11. Viewing the IE developer tools network tab shows that it spends 12 seconds in Gap.

My question is what is Gap and what is being done during Gap? I know it's described as "the time between completion of this request and the page being loaded" in IE, but I'm not sure what is meant by that.

Answer 1

The Gap Timing is defined in Using Windows Internet Explorer Developer Tools Network Capture:

The offset value that is taken when the response has been received. The duration is the time between that start time and when the end of the last request is associated with the original HTTP request.

An older resource on Chris Bowen's blog defined it more concisely:

Gap – Time between response completion to page load event.

The gap therefore is the amount of time transpired between last byte received, and the load event. Once the last byte has been received, other resources are likely to be requested by the browser. The load event won't be fired until all images have loaded, etc.

If this resource is online, I (and others here, I'm sure) would be happy to help you further identify bottle-necks in your performance and responsiveness.