pydata/pandas — pull request #8547 by immerrr (2014-10-13 08:18:02+00:00)
Title: PERF: upgrade khash lib to 0.2.8

This should close #8524.

The idea is that quadratic probing `i**2 + i` is faster than double hashing and can be shown to traverse all elements if `nbuckets == 2**N`.

This branch compiles and passes tests, but I haven't done any benchmarks yet.