datatables slow loading data

I'm very new to datatables and trying to wrap my head around my question is datatables loading data is very slow. I have about 250 rows and it takes anywhere between 20-30 seconds... Is it possible to load data to datatables some faster way?

here is my code please correct me if you see anything wrong:

I'm using DataTables 1.10.2

here is the complete source code.
https://gist.github.com/abuhamzah1/b734987f487fdbe68bf9

thank you for helping me better understand