Yes, there's a bit of a penalty to using Moose. However, it's only a startup penalty, not at runtime; if you wrote everything properly, then things will be quite fast at runtime.
Did you also include this line:
__PACKAGE__->meta->make_immutable;
in all your classes when you no Moose;
? Calling this method will make it (runtime) faster (at the expense of startup time). In particular, object construction and destruction are effectively "inlined" in your class, and no longer invoke the meta API. It is strongly recommended that you make your classes immutable. It makes your code much faster, with a small compile-time cost. This will be especially noticeable when creating many objects.1
2
However, sometimes this cost is still too much.
If you're using Moose inside a script, or in some other way where the compilation time is a significant fraction of your overall usage time, try doing s/Moose/Mouse/g
-- if you don't use MooseX modules, you can likely switch to Mouse, whose goal is to be faster (at startup) while retaining 90% of the flexibility of Moose.
Since you are working with a web application, have you considered using mod_perl?
1From the docs of make_immutable, in Moose::Cookbook::Basics::Recipe7
2See also Stevan Little's article: Why make_immutable is recommended for Moose classes