High CPU usage when increase the transcode buffer size

[dorice]

When I change the transcode buffer size from 400 to 600, the javaw.exe will eat up all single core usage.
The default value (400) is fine, the CPU usage of javaw.exe always <= 10%.
And I cannot resume playing when pause a video, seems the mencoder.exe process will exit when pause.
My TV is Panasonic P46ST32C, and I use the default profile.