Why is Windows so slow?

I (and others) have put a lot of effort into making the Linux Chrome build fast. Some examples are multiple new implementations of the build system ( http://neugierig.org/software/chromium/notes/2011/02/ninja.h... ), experimentation with the gold linker (e.g. measuring and adjusting the still off-by-default thread flags https://groups.google.com/a/chromium.org/group/chromium-dev/... ) as well as digging into bugs in it, and other underdocumented things like 'thin' ar archives.

But it's also true that people who are more of Windows wizards than I am a Linux apprentice have worked on Chrome's Windows build. If you asked me the original question, I'd say the underlying problem is that on Windows all you have is what Microsoft gives you and you can't typically do better than that. For example, migrating the Chrome build off of Visual Studio would be a large undertaking, large enough that it's rarely considered. (Another way of phrasing this is it's the IDE problem: you get all of the IDE or you get nothing.)

When addressing the poor Windows performance people first bought SSDs, something that never even occurred to me ("your system has enough RAM that the kernel cache of the file system should be in memory anyway!"). But for whatever reason on the Linux side some Googlers saw it fit to rewrite the Linux linker to make it twice as fast (this effort predated Chrome), and all Linux developers now get to benefit from that. Perhaps the difference is that when people write awesome tools for Windows or Mac they try to sell them rather than give them away.

Including new versions of Visual Studio, for that matter. I know that Chrome (and Firefox) use older versions of the Visual Studio suite (for technical reasons I don't quite understand, though I know people on the Chrome side have talked with Microsoft about the problems we've had with newer versions), and perhaps newer versions are better in some of these metrics.

But with all of that said, as best as I can tell Windows really is just really slow for file system operations, which especially kills file-system-heavy operations like recursive directory listings and git, even when you turn off all the AV crap. I don't know why; every time I look deeply into Windows I get more afraid ( http://neugierig.org/software/chromium/notes/2011/08/windows... ).

MSBuild does suck in that there is little implicit parallelism, but you can hack around it. I have a feeling that the Windows build slowness probably comes from that lack of parallelism in msbuild.

As for directory listings it may help to turn off atime, and if it's a laptop enable write caching to main memory. I'm not quite sure why Windows file system calls are so slow, I do know that NTFS supports a lot of neat features that are lacking on ext file systems, like auditing.

As for the bug mentioned, it's perfectly simple to load the wrong version of libc on linux, or hook kernel calls the wrong way. People hook calls on Windows because the kernel is not modifiable, and has a strict ABI, it's a disadvantage if you want to modify the behavior of Win32 / Kernel functions, but a huge advantage if you want to write say, graphics drivers and have them work after a system update.

Microsoft doesn't recommend hooking Win32 calls for the exact reasons outlined in the bug, if you do it wrong you screw stuff up, on the other hand, rubyists seem to love the idea that you can change what a function does at anytime. I think they call it 'dynamic programming'. I can make lots of things crash on Linux by patching ld.config so that a malware version of libc is loaded. I'd hardly blame the design of Windows when malware has been installed.

Every OS/Kernel involves design trade offs, not every trade off will be productive given a specific use case.

The reverse, incidentally, was usually okay. If you could build it with MSBuild, it usually worked in Visual Studio unless you used a lot of custom tasks to move files around.

I personally believe the fact that Visual Studio is all but required to build on Windows is one of the single most common reasons you don't see much OSS that is Windows friendly aside from those that are Java based.