Experimenting with replacing the explosion in attempts to cut lag of visible stompy pillars.
If switching to just the sound effect isn't enough, might go for something involving sounds and single block updates, like a skinny pillar of something coming down from the sky with a sound of rapid explosions.
We're going to try a pillar of lava accompanied by thunderclaps. The single pillar is causing much less lag, and lava is a damaging material that will set you on fire, plus it will briefly light up the night.