Sometimes serial, sometimes parallel

Hi All,

Anyone got any ideas why in this waterfall there are periods of serial download activity (e.g. resources 7-13) and in other places parallel (e.g. 13-18)?

Ideally I’d want resources 7-13 to load in parallel, just this would take over a second off the response time.

How to fix? Any help appreciated.


The page contents won’t download until after the CSS/JS needed to display the page are completely downloaded. However Chrome has a ‘look ahead’ feature that will guess what the browser will need to download, it will do this in serial or blocking, creating the waterfall you see.

This is why after the js file is downloaded, the resources will go back to loading in parallel. To decrease this impact you could split the large js file into two or more files.

Thanks clubberz, nice explanation.