With the rules saying that there are no restrictions on items, outside help, etc., I have leveled to 10, and even beyond, very quickly in this run. This is done without any glitches or cheats, of course! =]

Admittedly, I didn't stop the timer on time, but if you check the video you'll see that I hit level 70 (which is higher than level 10) around the 54-55 second mark. If you feel I should stick to the timer then I will accept a 1:26 time instead with full understanding.