When i lure mobs to my mage by using arcane missiles in quick sucession, i noticed that many mobs fail to reach me, standing like 5 whole feet away from me and unable to get into attack range.

We need more info on this, as it's the first report we get regarding this matter.
So please link the mobs here so we can check their AI.

Thanks!

tango, its basically every* mob in the game from the start all the way up to northrend, but only happens to my arcane mage. The only common point i can think of is arcane missiles spam.