I had about 3 or 4 lockups today on firmware 1.5.1. I installed it today before the shoot. Each time it was a Card 2 freeze (SD card, right?). Turning the camera on and off didn't fix it; only after removing the battery 1-2 times did it resume normal shooting.
I was shooting indoor portraits today with the RF 85mm. Something I noticed was that the lockup usually seemed to happen when there was a lull between shooting, when I was directing the subject or changing the position I was shooting from. Also, I noticed that the red light indicating that it was writing to card seemed to stay on longer than I remember. I think I need to reformat my card (Lexar Professional SDXC 128gb 2000x). Maybe it has something to do with the fact that I am writing RAW+JPEG to both cards (I meant to change it to one format to each card, but forgot).
As far as focusing goes, it did seem a bit better than I remember from previous shoots. But that may be because I'm using RF lenses now instead of adapted EF.