MC server usage too much CPU time

I though this happens since 1.5.x
It is not only happen in snapshot.
mc1.5.x is super lag than mc1.4.x

Not saying it's the problem, but your java is out of date

Is this still a concern in the latest Minecraft version 13w48b? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.

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