[Question]how to test speed of "Contain" by -O3 -march=native?

[huawendi]

I use the code to test the speed of looking up alien items, but the result is very high. Is it optimized by the compiler? How should I do ?
start = chrono::steady_clock::now(); for (size_t i = 0; i < num_inserted; ++i) { filter.Contain(aliens[i]); } end = chrono::steady_clock::now(); find_time = end - start;