CPU performance fluctuating under the cpufrequtils control

After an approximately 6 hours of oreration the CPU performance gets fluctuations leading to overall system performance degradation. The System Monitor's CPU usage history displays a saw-like CPU load graph, see the attachment.

 The cpufrequtils service restart recovers the performance.

The system thermal status is fine.
HW: Intel Core i3 processor + Intel H55 chipset.
 Switching governors e.g. "ondemand" to "performance" and back may provoke the bug.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: cpufrequtils 007-2
ProcVersionSignature: Ubuntu 3.2.0-67.101-generic 3.2.60
Uname: Linux 3.2.0-67-generic x86_64
ApportVersion: 2.0.1-0ubuntu17.6
Architecture: amd64
Date: Wed Jul 30 13:58:10 2014
InstallationMedia: Kubuntu 12.04.2 LTS "Precise Pangolin" - Release amd64 (20130214)
MarkForUpload: True
ProcEnviron:
 LANGUAGE=en_US
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: cpufrequtils
UpgradeStatus: Upgraded to precise on 2013-12-13 (228 days ago)