Suppose your BizTalk Maps are present in assemblies that are large (let’s say that 5 mb and above can be considered as large). You might run into the situation where the memory consumption of the BizTalk Host Instances executing such maps (either within an Orchestration, or on a Receive Port) grows quite large. If you do, then we’d like you to let you know that we’ve recently released a hotfix for BizTalk 2006 R2 (and are in the process of releasing one for BizTalk 2006 shortly). Try it out (http://support.microsoft.com/kb/975118)

NOTE that this hotfix is meant to solve problems only where the large memory consumption is due to the execution of maps within large assemblies. If you face this situation even in your test environment, then one way you can determine whether this hotfix would help you or not, is to let your BizTalk Host Instance run until it has consumed a sufficient amount of memory, then take a dump / attach a debugger and view the managed objects in the heap. If you see a large number of byte arrays, which are rooted within “System.Security.Policy.Evidence” objects, then this hotfix might help.