When the operating system has many threads running across all processes, and multiple BizTalk host instances are running simultaneously, thread enumeration in the throttling control component of the BizTalk Message Agent may cause high CPU usage in kernel mode of Windows. High CPU usage may occur in both in-process (BTSNTSvc.exe and BTSNTSvc64.exe) and isolated (w3wp.exe) host instances.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
This problem is fixed in the following cumulative update for BizTalk Server:
For information about the service packs and cumulative update list for BizTalk Server, see the following article in the Microsoft Knowledge Base:
2555976 Service pack and cumulative update list for BizTalk Server
For more information about BizTalk Server hotfixes, see the following article in the Microsoft Knowledge Base:
2003907 Information about BizTalk hotfixes and Cumulative Update support