sm::HashId speedup.

Before:
![screenshot from 2014-08-18 13 56 49](https://cloud.githubusercontent.com/assets/4147796/3951540/266481be-26d8-11e4-9ad0-32339a2c91bc.png)

After:
![screenshot from 2014-08-18 15 00 24](https://cloud.githubusercontent.com/assets/4147796/3951542/2c34a04c-26d8-11e4-925e-0bcf50300a00.png)