DISQUS

Luke A lot of the templating systems available now actually pre-compile your
templates the first time they get used - so while there is some overhead,
that overhead is negligible after the first hit on your template - if your
server is fast enough, the overhead from that initial hit should be barely
noticeable.
In my experience, programming languages are typically designed the way they
are to increase developer productivity - Templating systems are just another
addition to your toolbelt to increase that productivity - they aren't a
silver bullet of any kind.

Also, I would be wary of optimizing a little too early - your statement that
"it's an overhead on your server" sounds like you may be prematurely jumping
to the conclusion that your templating system is what is slowing your game
down. As you can see by looking at the benchmarks at
http://shootout.alioth.debian.org/u64/benchmark..., Ruby
and PHP aren't what you should be using at all if you're concerned about
performance(at least not on a 64-bit Ubuntu machine, anyway) - if you wanted
your game to be as absolutely fast as possible on the cheapest hardware,
you'd write it in C++.

At the end of the day, it's your game. If you'd rather not use a templating
system, then don't! Maintaining your code is only your responsibility, and
you(or your team) will be the only ones who see it(or even worry about it,
chances are). So do what you like - but know that templates come highly
recommended.