C で 2D std::vector の初期化を最適化するにはどうすればよいですか?

std::vector<std::vector<int>> fog;
for (int i = 0; i < A_NUMBER; i++) {
    std::vector<int> fogRow;
    for (int j = 0; j < OTHER_NUMBER; j++) {
        fogRow.push_back(0);
    }
    fog.push_back(fogRow);
}

std::vector<std::vector<int>> fog(
    ROW_COUNT,
    std::vector<int>(COLUMN_COUNT)); // Defaults to zero initial value

std::vector<std::vector<int>> fog(
    ROW_COUNT,
    std::vector<int>(COLUMN_COUNT, 4));

std::vector<std::vector<int>> fog { { 1, 1, 1 },
                                    { 2, 2, 2 } };