Just a dude with a shovel, looking for the past.
I started using a 2 minute sand timer and now I use table initiative. If any of the players beat my rolls they get to chose a side of the table and those players go in order until half of them gone. Then half my monsters go, then the rest of the party and then the last half of the monsters. If I win the initiative, I get to use half the monsters and then chose which half of the table will go. The results were surprisingly much faster with the party knowing when they were going. I ran a 5 vs 5 combat of pcs vs zombies in like 30 minutes total.