You are an exception. The fact that you applied online and got test invite does not necessarily mean that most online applications are fast. If you look at trends of recent months, the progress of paper applications has been faster.
For example, for the august applicants, 54% of all applicants were paper applications. If paper and online applications be treated equally, we expect 54% of all test invites belongs to paper applications. However, by computing what happened in reality, 67% of those who got test invite were paper applications. That's why I'm saying that they process paper applications faster.