As there was a huge voltage dropout on the 5v line (see previous post) I decided to replace diode bridge with schottky diodes I got from PC PSU long long time ago:
Wow, much, much better. Only 150mV voltage drop on 4.5A load — it’s totally fine for my goals with this PSU:
3.5A load — I would say no voltage drop (9mV):
Also included 12v line, without load:
1A load, almost no drop:
2A — 40mV drop, let’s say still almost no drop 
2.3A — 200mV drop:
Load:
