> So think about the system your code is running in, if things are getting parallelized at a higher level, it may not do any good to do it again at a lower leve

> So think about the system your code is running in, if things are getting parallelized at a higher level, it may not do any good to do it again at a lower level. Instead, focus on algorithms that run as efficiently as possible on a single core. Generally this is a extremly bad advice. Especially with: > What you forgot was that the web server was already parallelizing things at a higher level Apache parallized like that. and it was bad. Nginx then introduced a eventloop, which was way better. however your application still needs to deal with it. i.e. if one request is blocking (taking too much time) your nginx will block, too. if that happens on all worker threads your website will be extremly slow. A EventLoop mechanism always means that your stuff should be non-blocking and that is hard. this is especially hard when dealing with external resources, i.e databases, external services, caches, file io. when you just say "well my webserver will handle that" you will be in a really really bad shape.