Is speed of play the most important factor? I don't think it always is.
With Fantasy grounds in particular, I can use individual initiatives for each monster and it does not take any longer than it does to have them all act at the same time. Plus, it has the benefits of a) being more "realistic", b) increasing the chaos of combat, and c) keeping players engaged. I admit it would be pretty touch to do at an IRL table unless you have a super efficient method for tracking initiatives and declaring actions. But then running 20 orcs at the table would be a slow and laborious process anyway.