Thank you so much, Fiery, for the fast reply, that does the trick. There are 4 "remember this, remember that" boxes, this one was unchecked. Now Aida is working like before. Start time is 4 seconds, which is no issue for me. I like the sensor page better than other tools, the overview is fine.
The problem with IRST driver is, that unfortunately I own the Corsair 1200AXi which needs the buggy Link Software which gives you BSODs if using the newest IRST driver. So beware of this PSU. I uninstalled IRST completely and strangely - as a spin-off - my new SSD runs at the advertised speeds. Whereas with IRST my SSD was running substantially slower.
The right-click on the taskbar icon is a nice shortcut as well.
Best regards,
Verdi