SCCM 2012 R2 has some hotfixes you might need:

2905002

An update is available for the “Operating System Deployment” feature of System Center 2012 R2 Configuration Manager

This update resolves the following issues in Microsoft System Center 2012 R2 Configuration Manager.

Issue 1

After you enable the PXE Service Point role (http://msdn.microsoft.com/en-us/library/jj217832.aspx) on an instance of a specific distribution point, or you select the Deploy this boot image from the PXE-enabled distribution point property of a boot image, the Windows Deployment Service (WDS) stops running. Additionally, entries that resemble the following are logged in the Windows Application log:

Faulting application name: svchost.exe_WDSServer, version: 6.3.9600.16384, time stamp: 0x5215dfe3

Faulting module name: MSVCR100.dll, version: 10.0.40219.1, time stamp: 0x4d5f034a

Exception code: 0xc0000005

Fault offset: 0x000000000005f61a

Faulting process id: 0xae4

Faulting application start time: 0x01cec5d767184634

Faulting application path: C:\Windows\system32\svchost.exe

Faulting module path: C:\Program Files\Microsoft Configuration Manager\bin\x64\MSVCR100.dll

Note This problem affects only distribution points that are installed on site servers.

Issue 2

When operating system image files are downloaded to Configuration Manager 2012 R2 clients, you may find that the download takes longer than it did in previous versions of Configuration Manager 2012 clients. You may see this behavior when the target client is running Windows PE or a full Windows operating system.

2907591

Per-computer variables for imported computers are not read in System Center 2012 R2 Configuration Manager

Per-computer task sequence variables that are defined for imported computers are filtered out of client policies. This prevents the variables from being read during task sequence execution. This problem does not affect per-computer variables that are defined for existing clients.

2907566

November 2013 anti-malware platform update for Endpoint Protection clients

This anti-malware platform update contains the following improvements:

• Adds anti-tampering functionality to reduce the risk that malware will disable or bypass anti-malware scanning.  For example, access to files and folders that are used by the anti-malware platform can be changed only by trusted system processes or by the anti-malware platform itself.
• Improves overall performance of the anti-malware platform. Anti-malware performance is improved compared to that of previous platform versions. Improvements were made to scan functionality. These changes involve no configurable effects.
• Ongoing improvements to Microsoft Active Protection Service (http://technet.microsoft.com/en-us/library/ff823779.aspx) (MAPS) and Dynamic Signature Service (http://technet.microsoft.com/en-us/library/ff823908.aspx) (DSS). These make real-time cloud-based protection easier. Scale and performance improvements were made to the MAPS and DSS systems. Make sure that you opt-in to at least Basic or Advanced MAPS to make sure that you are benefitting from cloud-based protection.