Jefficient
Being 100% efficient with a 100% accuracy. Only a person named Jeff can be Jefficient.
Man look at Jeff work. He is definitely Jefficient.
jefficiency
A jankety version of efficiency where a person thinks that the way they do things is efficient, but in truth, is actually ineffective to a point of incompetency.
Their jefficiency is slowing us down. I can't believe they actually do it that way. It's like saving an email to your desktop for future use that has a link in it. Then opening the email, clicking the link, and closing the email every time you need it rather than just creating a shortcut.