Moose is a postmodern object system for Perl5. Moose is wonderful.

Unfortunately, Moose has a compile-time penalty. Though significant progress has
been made over the years, the compile time penalty is a non-starter for some
very specific applications. If you are writing a command-line application or CGI
script where startup time is essential, you may not be able to use Moose (we
recommend that you instead use persistent Perl executing environments like
FastCGI for the latter, if possible).

Mouse is a Moose compatible object system, which aims to alleviate this penalty
by providing a subset of Moose's functionality.

We're also going as light on dependencies as possible. Mouse currently has no
dependencies except for building/testing modules. Mouse also works without XS,
although it has an XS backend to make it much faster.