How do I create a global map projection with contours with x y z plots?

Hello, I have a .txt file (16471 x 3 double). Each column represents x y and z points. x and y are latitude and longitude and z are contour points. I do not have the mapping tool box and I used griddata to make Z at least a 2x2 matrix as needed when using contourf, but it takes a long time to load. Please help! Thanks!