string_stream with large string presset, C++ (vc++)

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#include <iostream>
#include <sstream>
#include <memory>
#include <iterator>

class LogHelper {
public:
    ~LogHelper() {
        std::cout << out.str() << '\n';
    }
    
    std::ostream &stream() {
        return out;
    }
    
private:
    std::ostringstream out;
};

#define LOG() LogHelper().stream() << __FUNCTION__ << '(' << __LINE__ << ")"
#define VAR(x) ", " #x "[" << x << ']'

class MyAllocator : public std::allocator<char> {
public:
    using base = allocator<value_type>;
    using base::allocator;
    
    value_type* allocate( std::size_t n, const void * hint) {
        LOG() << VAR(n);
        return base::allocate(n, hint);
    }
    
    value_type* allocate( std::size_t n ) {
        LOG() << VAR(n);
        return base::allocate(n);
    }
    
    void deallocate( value_type* p, std::size_t n ) {
        LOG() << VAR(n);
        base::deallocate(p, n);
    }
};

using MySStream = std::basic_stringstream<char, std::char_traits<char>, MyAllocator>;
using MyString = std::basic_string<char, std::char_traits<char>, MyAllocator>;

int main() {
    MySStream ss(MyString(255, 'x'));
    ss.clear();
    
    int x;
    ss << "423";
    ss << " 423";
    
    LOG();
    ss << " 423jlfskdfjl jfsd sdfdsfkdf dsfg dsfg dfg dfg dsfg df gdf gdfg dsfg dsfgdsfgds";
    LOG();
    ss >> x;

ss.clear();
    ss.str({});
    
    ss.seekg(0);
    ss.seekp(0);

ss << "1";
    ss >> x;

std::cout << x << std::endl;
    LOG();
    
    return 0;
}

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Compilation time: 1,98 sec, absolute running time: 0,32 sec, absolute service time: 2,32 sec