There is ton of information available for BizTalk Server 2009 performance optimization. I am attempting to summarize the content and links of what is available out there:

• BizTalk Server 2009 performance optimization guide: The BizTalk Server 2009 Performance Optimization Guide contains prescriptive guidance for optimizing BizTalk Server performance, based upon hands-on experience of IT professionals who have worked extensively with BizTalk Server. This guide contains four main sections: Finding and Eliminating Bottlenecks, Optimizing Performance, Scaling a Production BizTalk Server Environment, and BizTalk Server Performance Testing Methodology. The BizTalk Server 2009 performance optimization guide is available here.
• Video: BizTalk 2009 – End to end performance testing: These 2 video recordings are from the BizTalk 2009 launch and Massive scalability night at Microsoft in Stockholm on April 16, 2009. This session introduces the BizTalk Performance Testing Guidance. This session will provide a full interactive run through of the performance lab process. It will illustrate the tools and techniques and documentation that we use and are documented in the guide. Also learn about performance lab characteristics on BizTalk Server 2006 R2, BizTalk 2009 (physical) and BizTalk 2009 on Hyper-V platform. Watch it here: Part 1 & Part 2.
• Presentations from the BizTalk Customer Advisory Team: There are 4 separate presentations available:

1. BizTalk Server 2009: Performance Characteristics on Hyper-V and Physical Platforms; Ewan Fairweather and Paolo Salvatori
   The BizTalk Customer Advisory Team quantifies performance of BizTalk Server 2009 vs. BizTalk Server 2006 R2, as well as performance of BizTalk Server 2009 on Hyper-V. The team also provides guidance on how to effectively do performance testing of BizTalk Server 2009.
2. BizTalk Server 2009 Performance; Ewan Fairweather, Tim Wieman, and Paolo Salvatori
   The BizTalk Customer Advisory Team provides examples of successful performance labs. The team also provides information about the tools, techniques, and processes that were used to run effective BizTalk Server performance labs.
3. BizTalk Server End-to-End Performance Testing Guidance; Ewan Fairweather and Paolo Salvatori
   The BizTalk Customer Advisory Team discusses how they run BizTalk performance assessments, demonstrate tools and techniques that used during the assessment, and introduce the BizTalk Server Performance Optimization Guide.
4. BizTalk Hyper-V Virtualization Guidance; Ewan Fairweather and Clint Huffman
   The BizTalk Customer Advisory Team shares best practices for using BizTalk Server with Hyper-V. They also provide guidance on the performance characteristics of BizTalk Server on Hyper-V, and introduce the BizTalk Server Hyper-V Guide.

Download them all from here.

• Technical Webcast: Ewan Fairweather, who is a member of BizTalk customer advisory team and is primarily focused on BizTalk Server performance, is presenting a webcast on BizTalk performance this Tuesday September 01, 2009 1:00 PM Pacific Time along with Trace Young, who wrote the majority of the BizTalk Documentation.  They will cover a summary of all the performance tests they have performed in the lab this year and answer any questions.  Please tune in if you have any performance related questions or if you just want to see what we have been up to.  Registration link is here. I will update the link once it is available for on demand.

Please do leave comments, if any questions or issues or suggestions. Thanks!