I don’t know for sure but it looks like taking pictures with the companion app slows down my avatar for a second. When pressing the camera button on the companion app Zwift hangs for a second on my PC, then the camera shutter sounds and I have lost draft within a group and fall behind.
Someone else experiencing the same behavior?
This problem depends on the speed of your pc. Usually I „loose“ parts of a second. I had a problem with my pc this week and it took 2 minutes to take a picture. Found out that my pc took so long to save save the picture-file. While saving the file, the map on the companion app froze and the picture on the PC screen too. I am sure if you use a faster pc you will not loose as much. 
Thanks for your comment. Well, I think I won’t make any photo’s during racing anymore due to this problem. That’s a cheaper alternative than buying a new hardcore gaming PC ;).