> I would think/guess you weren’t fully building from scratch, but from intermediate snapshots. If Linus pushed a commit, would your full build, minutes later, use it?

Yes, I would frequently download e.g. new kernel release tarballs (this was before Git) and slot it into the system. This didn't require recompiling anything but the kernel. Actually installing Stage 1 Gentoo required compiling everything (although it was on top of a compiler binary for bootstrapping.)

My hardware was cheap 2001 era consumer hardware, so I doubt it was that much faster than what the Windows developers had available. Besides, my question is more about why Windows (or anything else) would be difficult to compile, rather than just time-consuming. The nice thing about recompiling an entire operating system from scratch is that there are no external dependencies, because you're building everything! (Except the bootstrapping compiler, but for the Windows operating system there's no reason to rebuild that.)

Back in 2005 or so i was building freebsd, x11 and kde from scratch without issue. But these os’ are better engineered as there are no managers getting in the way.

Linux distributions put together the products of a a huge and very loosely organised community, and I never heard it was anywhere as horrible as these (old) horror stories of Windows development. Is it perhaps the case that the (enforced) loose coupling of open source development prevents the aggregation of build complexity and intermingled dependencies?

Why would those runtimes be particularly large? I'd expect the Win32 runtime to be large, but the others should be tiny by late 90s standards. Also, I remember that Windows didn't embed that many drivers itself, but that it had a stable ABI that hardware vendors could target (I remember driver CDs). Further, while the Linux kernel is certainly smaller than all of Windows, my point of comparison was compiling an entire desktop Linux system, which also included a full set of compilers, a desktop environment like KDE, office suites, multiple browsers, etc. Someone working on Windows 2000 shouldn't have to compile all that stuff.

My main question is also not so much why compilation of Windows should be time consuming, but why it should be difficult.

> Also, Windows had drivers for a lot more hardware than Linux did.

Did it? It had more third party drivers, but did NT itself build in that many?

NT had a HAL and that's it, with VERY few drivers on its own.