This would be an option, but setting an effect to the horse requires an extra packet for each horse and player and might just be too expensive in comparison to the benefits. This API wasn't actually made for handling such a high number of blocks. When spawning the blocks at once you're actually DDoS-ing the client with packets, eventually bringing the client to fall. However, your approach with the timers is a very good idea. EDIT by Moderator: merged posts, please use the edit button instead of double posting.