The tree conversion does not affect performance at all. It is only done on DOS attacks, which almost never occur. Counting the collisions is almost for free. T

The tree conversion does not affect performance at all. It is only done on DOS attacks, which almost never occur. Counting the collisions is almost for free. The optimizations are cache friendly open-addressing with linear probing, storing the hash, and power of 2 sizes. Another usual optimization would be a sorted array instead of the linked list.