This question already has an answer here:
Often times there are multiple good comments on a question and you want to upvote them all. However, you can only do one every 5 seconds. I presume this is to prevent spam (especially from bots). However, based on how the rest of the site works, restrictions such as these are suppose to go away as the user gains more rep and becomes more trusted. So why not just have a point where the site says 'you are trusted enough to not upvote spam, so upvote as fast as you want`, though still have the limit of 30 per day?
Edit: Yeah, chaning the coment system to x every y seconds is an alternative answer, but Im something different - removal entirely based on rep. I think it would work better.