Those process (Cat4k Mgmt HiPri, Cat4k Mgmt LoPri) are normally high
because of the way the CPU is managed on 4000/4500 technologies, let me
share with you the following information about it:
http://www.cisco.com/warp/public/473/cat4500_high_cpu.html#understand

This show processes cpu output shows that there are two processes that
use the CPU- Cat4k Mgmt HiPri and Cat4k Mgmt LoPri . These two processes
aggregate multiple platform-specific processes which perform the
essential management functions on the Catalyst 4500. These processes
process control plane as well as data packets that need to be
software-switched or processed.

In order to see which of the platform-specific processes use the CPU
under the context of Cat4k Mgmt HiPri and Cat4k Mgmt LoPri , issue the
show platform health command.

Each of the platform-specific processes has a target/expected
utilization of the CPU. When that process is within the target, the CPU
executes the process in the high-priority context. The show processes
cpu command output counts that utilization under Cat4k Mgmt HiPri .  If
a process exceeds the target/expected utilization, that process runs
under the low-priority context. The show processes cpu command output
counts that additional utilization under Cat4k Mgmt LoPri . This Cat4k
Mgmt LoPri is also used to run background and other low-priority
processes, such as consistency check and reading interface counters.
This mechanism allows the CPU to run high-priority processes when
necessary, and the idle CPU cycles that remain are used for the
low-priority processes. To exceed the target CPU utilization by a small
amount, or a momentary spike in utilization, is not an indication of a
problem that needs investigation. However in our case its high. It seems
that you may have hit a software bug CSCdz50987. This bug was fixed with
release 12.1(14)EW.