Server started to output "Cannot keep up" messages as I was logged in the server all alone. CPU was maxing out according to htop and I did an "debug dump file"
My character was just sitting. I toggled downfall on before the test and during the test toggled it back off, it didn't do anything to the cpu usage.
Fresh world, for 14w26c
Debug file included.
Edit. After I logged off the cpu usage went down.
Environment
java version "1.8.0_05"
Java(TM) SE Runtime Environment (build 1.8.0_05-b13)
Java HotSpot(TM) 64-Bit Server VM (build 25.5-b02, mixed mode)
java_jre/jdk1.8.0_05/bin/java -server -Xincgc -Xmx2G -jar minecraft_server.14w26c.jar
Linux Debian Wheezy
Intel i7-4770
Gone on 14w28a