Every time I speak I will mingle with the audience during the breaks and when they arrive and I will memorize as many names as I can. 100 names is pretty easy and with more work have done as many as 300 at a conference.
It is a simple process that I’ve perfected over the years of imagining images on the faces to remind me of their names.
For example, Lisa is the Mona Lisa, Brian is a brain and Karen is a carrot.
It sounds crazy but check it out.
(Then schedule me to speak for your conference!)