rustc is slow on Windows XP

On my 1.7GHz x86 WinXP laptop, rustc 0.5 ( the official binary ) takes 7.2 seconds to compile the "Hello World" from http://www.rust-lang.org/ . Even simply running "rustc -v" takes 5.8 seconds. During these operations, the CPU is 100% utilized and my system performs hardly any disk I/O. I have spare physical memory and no other tasks are hogging the CPU. I'm using a fresh install of the recommended MSYS version, and otherwise don't have any performance issues with the system; in comparison, "g++ -v" takes around a tenth of a second. The results are from several consecutive runs of the programs, and are very predictable.

On the same machine under Linux, "rustc -v" takes 0.03 sec, and compiling the "Hello World" -- around 1.6 sec.

This seems to be an issue with MinGW itself. I'm observing a very similar timing difference when running clang compiled with MinGW, and comparing to a version built by Visual Studio. The latter is snappy, whereas the former takes seconds to display the version number.

This is relevant: http://forums.wxwidgets.org/viewtopic.php?f=19&t=35542

[bstrie]

Related to #1768

[catamorphism]

@h3r2tic 's observation suggests LLVM may be the issue. Probably the first step would be to run with -Z time-passes and figure out which stage is taking up most of the time.

[catamorphism]

This is vague, and the eventual goal is to switch away from MinGW anyway. Closing.