The advantages to dyanmic prediction of kernel needs in Vista, especially with the "learning" of a users likely usage patterns, as you say does improve performance.
The fact is, network performance on Vista SP1 and Win Server 08 is over 300% from XP. Sure MS used that metric to spin up its marketng but the science of it remains.
As for boot times I respectfully dont accept your test results Humpty because honestly all of the tests Ive seen that showed Vista to be slower on boot than XP did not have comparable configurations. There is alot of things going on Vista that are not immediately obvious. There is numerous new things in the Vista boot process that make it faster. Not all of them are in the Linux kernel yet either.
I encourage you to look at objective performance rather than subjective performance. Do some network tests and see the metrics for yourself

I havent looked into any registry tweaks for Vista kernel behaviour.