What is the most optimized perms plugin ?

Hi all,

I'm using Spigot for some time now, and I'm currently building a Bungeecord configuration with 5 servers.
I'm familiar and perfectly fine with PEX, but I have a question:

What do you think is the best perm plugin to handle superperms on Spigot ?
I mean the one that is the most optimized speaking of timings.

If possible I'm interested in md_5's point of view too

Thank you.