To get faster, first make sure you're using a good 2x2 (either a DaYan or one of the MoYu ones), and then make sure you're using a good method (such as LBL with 1-look OLL and 1-look PLL, or Ortega). These methods total about 12-15 algorithms, and can get you to around 3 to 5 second averages with practice. If you want to get world class, you'll eventually need to learn CLL, EG-1, and EG-2, which are 42 algs each. For reference, the world class people average around high 1s to low 2s, as far as I know. Don't let those times discourage you though. 3 weeks really isn't that much time to be cubing, and it took all of the world class people a long time to get where they are. If you really care about 2x2, put in a ton of practice, learn these methods, and eventually you'll get there.