I am focusing on a Wordpress-powered website (has not gone live yet). More often than not after i load the house page it's fine. Sometimes, however, it freezes for any second on load, before ongoing normally. How do you debug this problem?

First I'd profile your php performance with:

  • xdebug using exterior tools like cachegrind

Next I'd also perform some base tests with:

Are you currently testing it on the server or in your area?

I have experienced this while developing on the local server, and it is the database access lag usually.

Chrome includes a developer tool that allows you profile the page and find out the length of time the browser stays on various things. Its situated under developer tools and it is known as timelines.
I believe firebug for opera can perform exactly the same but I have not used that.

Large exterior assets that need a reflow may block content. Search for complex javascripts and embedded fonts additionally for your general performance analysis.