pydata/pandas — comment on commit 4ec8e40affd7028a78b9472bf3ad5ac69ca63f91
File: pandas/src/datetime.pyx line 1621
By wesm:

this is not that interesting because you've cached an array that takes up a lot more memory than the timestamps themselves. it might be something we could toggle if a user plans to do a lot of field accessing and doesn't care about increased memory usage