Same issue here. I experience the same behaviour from kernel version 3.6.8 up to the current one : "3.6.11-1-ARCH #1 SMP PREEMPT Tue Dec 18 08:57:15 CET 2012 x86_64 GNU/Linux".I tried OpenJDK 1.7 and Oracle JDK with same results. Changing the JVM allocated memory helped a bit by reducing the blocked phase duration.
This issue may be related to Syslinux 6.02, which has been identified and fix in the latest ISO. See https://bbs.archlinux.org/viewtopic.php?id=173665 and https://bbs.archlinux.org/viewtopic.php?id=172588 for further information.