Critical Mass seemed paced about right for a) digestion and b) avoiding collisions with other riders. Just.
The problem with CM is that it's full of people with limited group riding experience, moving so slowly that you don't tend to leave a lot of room, on bikes with riding dynamics you can't predict (you can spot the fixies and the serious mountain bikes, but can't reasonably guess how well anyone else's brakes work). All it takes is for a couple of wheels to touch, or an unexpected pothole, or a rider locking the back wheel and causing the person behind to brake sharply, or someone to swerve in response to feet appearing in their peripheral vision
[1], for it all to go a bit wrong. Fortunately, at those sort of speeds it's only usually people's phones or bike lights that get properly injured.
[1] While the recumbent is cool, it's a poor choice of bike for this sort of riding. I only do it because I've had a lot of practice riding slowly, check my blind spots obsessively and try to be as predictable as possible, which is how I always end up at the back of the group.
