Is the process of the Steps painful?
In my experience, no. There is not one element of the AA experience that is painful, in itself.
Actions, especially confession (Step Five) and amends (Step Nine) can be very uncomfortable in the moment, but they're like the pinpricks of injections or the pain of having a sticking plaster ripped off: the pain so rapidly yields to relief and other feelings that the 'pain' becomes almost enjoyable, a sign that release is on its way.
Every single dose of grinding, intolerable, unceasing pain comes not from the programme but my resistance to it, to some principle, to God's will, to reality, or to my perception of reality.
The widow in the Bible puts in her two mites and she's done. That's all she's got but it's all she gives.
Anyone who does not do that will see their universe crumble, slowly, and painfully. I've had that happen many times.
This need not be, ultimately, with some practice in surrender.
When I let go absolutely, I'm instantly absolutely fine.