Wolf, I may have said this before, but I’m sorry for your loss.
I usually tried to move near one or more of the other aveilim, so we could say Kaddish at the same pace. The other person, in the beginning, had a real problem saying it, so I made sure to go slowly enough so he could say the words.
If anyone else wanted to say it faster, we let them, and just continued at our own speed. I think people understood what we were doing. I certainly never heard anyone complain that I said Kaddish too slowly. (The same, unfortunately, can not be said for times when I was shaliach tzibur – some complained I was too slow, others said I was too fast.)