The thing with frameworks/platforms like Wordpress is that they give you a lot "out of the box" ... but you will want to tweak that to give your site an original feel.
From a performance perspective frameworks with plugins have to abstract their design to allow loading of plugin/module code so they tend to be less efficient. ANd if your page takes longer than a second to load, many users have bounced already!
Of course ... a bad programmer could build a custom page that is even worse... it's been known to happen :rolleyes2:
Try to validate your finished (is a website ever really finished?) website against validators such as Google rich snippet validator, the 3WC validator, etc .. to get the optimum performance and stability on how your visitors experience your website.