So I started a new char as a pure mage and on my second playthrough I decided to complete all of whiterun's quests before I go on exploring and such. I am level 8 and have finished all of the whiterun main quests and side quests. It took me 6 hours and the problem is on my first playthrough I remember playing for a good 12 hours simply doing whiterun quests and ended up somewhere around level 12-14.

I understand that I know what to do now and that explains the quick time, but why the slow growth.