Screen shot is linux "top" command. Both servers are with the same world, same everything actually, just in different folders, and using different minecraft_server jar files. Both servers have 0 players logged into them.

One is green is 1.7.10 minecraft_server file, the one in Orange is 1.8 pre 1 minecraft_server jar file.

When players log on, the 1.7 server is only about 40 to 60% cpu, but the 1.8 goes to 200 to 250%.. Screen shot is with 0 players logged in though.