Identifying Performance Bottleneckshttp://msdn.microsoft.com/en-us/library/aa578679.aspx
Threads, DB sessions, and throttlinghttp://biztalkperformance.members.winisp.net/BlogPages/MaxWorkerThreads.htm
The number of running orchestrations increases and then remains constant after you reach the thread pool limit, and orchestration execution time may increase in BizTalk Server http://support.microsoft.com/kb/900455
Configuration Parameters that Affect Adapter Performancehttp://msdn.microsoft.com/en-us/library/aa561380.aspx
Suspended Messages are Included in the Message Count in Database Throttling Thresholdhttp://msdn.microsoft.com/en-us/library/aa577623.aspx
MSBTS_HostSetting.ProcessMemoryThreshold Property (WMI)http://msdn.microsoft.com/en-us/library/aa559112.aspx
How to Configure the DTA Purge and Archive Jobhttp://msdn.microsoft.com/en-us/library/aa558715.aspx