Crashing servers by switching item in offhand

Apparently there is an exploit known by server owners that allow you to crash a server by switch items really fast. It was being discussed in the Minecraft lounge (NDA channel) along with a plugin that fixes it by limiting the amount of times that packet can be send to 3/10 per second
https://www.spigotmc.org/resources/packet-limiter.70217/

This can also cause individual clients to crash on top of the server according to reports

I dont have a script or a server to test, so feel free to change the reporter