[subbu_ss]

No, we haven't investigated it yet since we haven't had the time to do it. But, we've filed a task for maybe someone to look at it ( https://phabricator.wikimedia.org/T241968 ), but our hunch is that it would be be incorrect to conclude that PHP is faster from JS.

[cscottnet]

A slightly longer answer is that we looked into a number of possible reasons and it's not clear there's an easy answer. Lots of differences between the two setups, and every time we come up with an possible answer like "oh, it's the reduced network API latency" we come up with a counter like "but html2wt is also faster and it does barely any network requests". Casual investigation raises more questions than answers. So we've looked into it but don't yet have an answer that we fully believe.