Speed of PHP vs JavaScript?

Well, like you alluded, JavaScript is executed on the client side, so it would depend on the client. For example, a client on an iPAD wouldn't be able to run those Quake3 HTML5s as smoothly as a client running on a gaming machine. PHP on the other hand runs on the server.

In general, JS is faster considerably than PHP though (on the same hardware);

Here are some [hard figures][1] of tests between the two, to back up my assertion. [JS (query) vs PHP][2] Performance.

[1]: https://benchmarksgame-team.pages.debian.net/benchmarksgame/fastest/php.html [2]: jQuery vs. PHP - Performance Comparison

I just converted a script from PHP to Javascript and I have greatly increased performance.

Javascript seems much faster in mathematical calculations. I have personally witnessed the performance improvement, my PHP procedure in some cases also employed a few seconds of running, while the same procedure written in javascript takes at most a few milliseconds.

Although Javascript to be known as client-side language I run my code on the server side thanks to Node.js

Its worth saying that another consideration for using PHP is the ability to cache server side. I'm looking at this considering if I should move some of the functions from JS to PHP because if I then cache the files server side there is no further calculations involved at all! I know this ticket is old but this may be another consideration for future readers.