+1 Remove it as quickly as possible. It hurts my eyes.

Do not remove. Just make it little less annoying. The idea is great. With all lag issues it is extremly helpful to see if the fastest spells were really casted. It would be great to see parallel effect on health and mana potions which have another buffer.

It could only affect the spell which was lastly used, far enough to check.

And ofc the best would be to let player choose in options, between nothing as before OR whole bar animation OR only last spell animation)