For users on high latency connections, parser-blocking scripts loaded via document.write cause significant delays in user perceived page load latency.

Most scripts inserted via document.write are for third party content. A quick survey of the third parties suggests that async solutions are commonly offered. Given how bad the user experience can get for users on slow connections, it's quite likely that a large fraction of page visits never succeeds. The hope is that these newly rescued page views would incentivize publishers to adopt async solutions.

Chrome is exploring the following intervention:

• for users on slow connections, block network requests for document.written scripts
• design doc
• crbug