Average Tick skyrockets in 14w30b/c

I run a small server on a home computer, and as of the 14w30 snapshots the server is unplayable. People can join the server, but as they stay on the average tick goes through the roof to ~150ms. Anyone who is playing is disconnected, but since the server is lagging so bad it doesn't recognize that people have disconnected. If those people join again you see the glitch where there are two characters - one does work the other does nothing.