c++performancec++11boostboost-regex

std::regex is much slower than boost::regex on VC2015U3

std::wregex EXCEL_CELL_REGEX(L"=\"(.*)\"", std::regex::optimize);
std::wstring text = L"=\"300498\"";
for (int i = 0; i < 981 * 6; i++) {
    std::wsmatch match;
    std::regex_match(text, match, EXCEL_CELL_REGEX);
}

Above code takes about 9 seconds

boost::wregex EXCEL_CELL_REGEX(L"=\"(.*)\"", boost::regex::optimize);
std::wstring text = L"=\"300498\"";
for (int i = 0; i < 981 * 6; i++) {
    boost::wsmatch match;
    boost::regex_match(text, match, EXCEL_CELL_REGEX);
}

Above code takes about 1.5 seconds

Those tests are built on Debug configuration.

Do you know why std::regex is so slow? How to optimize the code?

Solution

  • Debug execution times are useless; they are often completely divorced from real-life performance of the Release build. Also, debug times will be extremely system- and compiler-dependent.