Avoid large reallocations in webserver's header response by d-a-v · Pull Request #8873

Avoid large reallocations in webserver's header response by d-a-v · Pull Request #8873 · esp8266/Arduino

at a glance, we have a bunch of typed pairs that generate multiple emplace_... for every sendHeader variant
I'd consider using perfect forward and a specific type we already have

using Pair = std::pair<String, String>;

auto foo(Pair pair, bool condition) {
    if (condition) {
        foo(std::move(pair));
    } else {
        bar(std::move(pair));
    }
}

template <typename S1, typename S2>
auto foo(S1&& name, S2&& value, bool condition) {
    foo(std::make_pair(
        String(std::forward<S1>(name)),
        String(std::forward<S2>(value)), condition);
}