All enchanted items and potions have the glowing effect applied. When the enchanted item/potion is held in the hand, the FPS drops rapidly. When a command block gives a player 64 filled potions (e.g. speed potion), the game suddenly hangs. This has rendered some adventure maps unplayable. Also, when an enchanted bow is pulled, there is a decrease in FPS. This means that the fps drop is caused by the glowing effect, as normal items (without the glowing effect) do not affect the FPS. This bug has been prevalent from 1.6 onwards and it never got fixed. Please fix this bug as it would greatly remove the hinder from our Minecraft experience.

Attached is a picture showing the glow effect.