Use std::locale::classic() instead of creating new C locales on demand #1370
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jbeder
approved these changes
Sep 17, 2025
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I noticed that parsing yaml documents with floats is quite slow when compiling for wasm with emscripten. It turns out that the calls to
std::locale("C")that are used inconvert<float>take more than 1ms each in emscripten. To fix this I replaced the creation of the locale with a call tostd::locale::classic()which returns a static reference to an already initialized C locale (see documentation). This reduces the parsing time by 85% for me.