"Among the big changes are improved scalability and performance
improvements, thanks to a new threading subsystem that is optimized
for multi-core systems. The NetBSD kernel itself has been improved
to include kernel preemption, a new schedulers as well as some
""Almost all core kernel subsystems, like virtual memory, memory
allocators, file system frameworks for major file systems, and
others were audited and overhauled to make use of highly concurrent
algorithms," NetBSD 5.0's release notes state."