问题
As you can see the second request starts 784ms after the beginning. I wonder why that request starts at 784ms instead of 741ms (directly after the first one)?
What happens in the 43ms in between the first and second request? There is no indicator showing that there is a blocking request.
回答1:
The 43ms between the two requests indicate the parsing time. I.e. this is the time needed to process the request to the page URL you requested and find embedded resources like images, JavaScripts, etc., which need to be loaded.
So there will always be a gap between the first request and the second.
The same happens for requests to other resources like CSS files. Their contents first need to be interpreted after their download to know the other resources they include like e.g. images, web fonts or other CSS files.
来源：https://stackoverflow.com/questions/28029870/what-does-the-time-elapsed-between-network-requests-mean