The site not really slow. What happens is that the load some pages is slowed by advertising.
Advertising is served using Javascript that fetches ad content from remote Web servers of the advertising agencies like Google AdSense, Tribalfusion, Fastclick, etc..
Nobody likes advertising precisely for that reason. Advertising slows down the load of the pages and distracts users.
Unfortunately, for now advertising is necessary to keep a busy site like this financially viable.
Fortunately, there is now an alternative for those that are intolerant to advertising. If you would like to access the site without being slowed down by advertising the site provides premium subscriptions.
The premium subscribers can benefit from better services, which include among other things the ability to access the site pages without any advertising.
Premium subscriptions are not free, but they are neither very expensive. They cost at most USD $5/month or USD $4/month if paid annually.
Besides not being exposed to advertising, you can benefit from several very interesting services like being listed as a featured PHP professional in the PHP professionals directory:
phpclasses.org/professionals/
If are not sure becoming a premium subscriber is worth the benefits, you can request a premium trial subscription that lets you try premium subscriptions for free during a few days.
You may learn more about free trial subscriptions and other premium subscription benefits in this page:
phpclasses.org/premium/
Just let me know if you have more questions.