> - some basic facts about modern CPU architecture: why self-modifying code is
 > very slow, why computed and indirect branches are slow.

A good book on modern CPU architecture is "Computer Architecture: A
Quantitative Approach" by John L. Hennessy and David A. Patterson
published by Morgan Kaufmann. ISBN: 1558807242. It's about 900 pages
but the chapters can be read individually. It's a tour through current
hardware design from CPU pipelines to building clusters. For the
fundamentals today it's probably the best thing available.

For details on the instruction sets the guides produced by AMD and
Intel are fine both are freely available on the web. They include
everything that you'll need to know about the x86 instruction set.
Either companies instruction set guides are good, I think Intel's are
better. AMD's optimization guide is better, it has a lot more detail
on what's going on. Intel's optimization guide has too much space
dedicated to top tips and too little to how things work.

http://www.amd.com/us-en/Processors/TechnicalResources/0,,30_182_739_...

http://www.intel.com/design/pentium4/manuals/index_new.htm

Branch predictor information is harder to find. There's definitely
information available but I don't have links handy. "Computer
Architecture" covers the techniques.

Bryce