It surely will increase the server load a bit but you could as well say I am just serving static pages because of that.
Php is great, I'd strongly recommend that you start using it. The thing I like most is it is pretty easy to learn, there is no chmod stuff as with perl scripts, and you have all the code right in the html pages, not in separate files distributed all ver the place.
I have almost no page WITHOUT php and can't see a huge difference in server speed. And you always could upgrade the cpu and RAM in case you need it.
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