Fixed bug where tableMaps were not cached.
#478 - Performance increase from 16,252,928bytes/3.284s =>  12,058,624bytes/2.170s
Removed slow in_array and replaced it with isset for `modifiedColumns`.
#478 - Performance increase 100ms
Removed slow call_user_func and replaced it direct call.
#478 - Performance increase 50+ms
Merge pull request #479 from marcj/perf

Perf