Some post SP2 hotfixes install an old version of the nrdhtml.cab file
The installer of the affected hotfixes contains a problem that causes the nrdhtml.cab file to be replaced with an old version (version 5.0.4526.0). This can cause performance problems during authoring as the cab file is downloaded for every placeholder control again and again.
Workaround: backup the original version of the nrdhtml.cab file installed when installing SP2 (version 5.0.5054.0) before installing a hotfix and then restore this file after installing the hotfix.
The hotfix for this request has been released and can be requested from Microsoft Support as KB 923755