The average XP you get from 1 hour of playing infected is 10800 or less.
Meaning after a whole day you will receive 259 200 XP
To prestige you need about 1700 000 XP, so you need to leave your PS3 on for A week Exactly to prestige.
Now if the game kicks you, your PS3 gets YLOD, your power bills gets bigger or anything like that is an other story..