That's php for you. Although I use php myself quite often, it can be a resource hog if you're lazy about optimization. A customer I was working with was using wordpress, and their homepage took about 5 seconds to load due to a hideously inefficient wordpress module that was doing the exact same sql query thousands of times! With a little bit of optimization I managed to get it down to about 1 or 2 seconds.
For my own sites, I mostly use static html or server-parsed html.
Of course I'm aware of that. I was just giving an example of a specific case I came across. The point I was making is that there is a lot of inefficient php code out there.
Recently a colleague and I took a PHP+MySQL page that was taking 1-2 minutes to load and were able to drop it down to 30 seconds after our first round of revisions. After a second round of revisions, we got it under 15 seconds, then after another round we got it to the 1-5 second range. Most of the optimizations were in the PHP not in the SQL.
I came to make the same point - but PHP itself is not directly the problem.
There are many, very popular Wordpress plugins that take hundreds of SQL queries just to render a landing page. 10 hits/sec legitimately is "DDoS" territory for many businesses running such things.
For my own sites, I mostly use static html or server-parsed html.