message: Added a performance section
diff: @@ -92,3 +92,13 @@ make install
  cd [Debug | Release]
  make uninstall
  ```
  +
  +### Performance
  +There is a test program [dataframe_performance](test/dataframe_performace.cc) that should give you some sense of how this library performs. It does the followings in about 300 to 400 milliseconds on my mac-book
  +![Alt text](docs/MacSize.png "About MacBook")
  +
  +1. It generates about 16 million second resolution timestamps and loads it into the DataFrame
  +2. It generates about 16 million random numbers each for 3 columns with normal, log normal, and exponential distributions and loads them into the DataFrame
  +3. It calculates mean each of the 3 columns
  +
  +The program is compiled with gcc compiler with -O3 flag
  