Benchmarking the Library

### What is wrong?
I personally think that it would be better if there were some `benchmarks` added to this library, so that to make sure that we are not altering any optimizations made etc. while adding new functionalities. Further this is a pretty primitive module where I believe speed matters.

### How can it be fixed
I think we could something similar to what we are doing [here](https://github.com/ethereum/py-evm/blob/master/scripts/benchmark/run.py)