package function calling

BarMeister has asked for the wisdom of the Perl Monks concerning the following question:

Are there any performance benefits/issues with doing the following?

use MyPackage::MySubPackage;
MyPackage::MySubPackage::some_function();
[download]

...as opposed to...

use MyPackage::MySubPackage;
some_function();
[download]

I am using mod_perl, use strict/warnings, etc...