Wearing light armor lowers movement speed by 1% per piece
Wearing any amount of light armor increases magicka costs for spells depending on the spells level, 10/20/30/40/50% extra cost for novice-master respectively. This penalty can be negated by having the perk "Agile Spellcasting" in the Evasion tree, though costs will still be increased by an amount proportional to your effective mass.Â