I cannot reproduce it easily since it happens once in a while and only in our private instance. Cannot paste the test link (since its private instance) but waterfall is pasted as a screenshot.[attachment=833]
was your test running on the same machine, same browser all the time?
Remember JS, CSS execution time depends on client machine's CPU and memory.
I also notice that walmart's base page is running on HTTP/2 protocol.
Does walmart still have HTTP/1.1? If yes, you might want to try if this can be reproduced on HTTP/1.1.
But my main concern is that why the page stays blank for 2 seconds based on my test below. https://www.webpagetest.org/result/18072...b731bb27b/
there are 20 assets contribute to the blank page.
there is a huge JS file (almost 0.5MB despite it's already compressed) on line 10 taking 1.5s to download + execution time.
I would suggest you profile all JS files that are in the the first 2 seconds.
I suggest to use Windows Performance Toolkit (free from Microsoft) to do JS profiling and do it on a medium size machine with warm cache.