why crf_test took long time

[cmathx]

I use a machine with 64GB memory and it has only 12GB memory. I run a test with tagger->parse() and it costs long time about 150ms. But when I run a test in machine with enough free memory, it only costs 2-3ms.
I find that most of the time spend on feature_index_->buildFeatures(this) and buildLattice() operations.

[Naminwang]

My machine has enough free memory, but parse() cost long time about 200ms. Do you find how to speed up the parse() interface? @cmathx

[cmathx]

You can focus on mmap function in the resp. A little case costs much time is because mmap call method.