Major performance issues with Burning Ground

I'm playing a Grenade build with Black Powder Blitz from the Shankgonne boots. It seems one of the most optimal ways to play it requires me to use lots of Oil Grenades to cover the ground in oil, then turn the Oil Ground into Burning Ground with Black Powder Blitz. It does decent enough damage, but the problem is that every individual pool of Burning Ground from every individual Oil Grenade spawns a new Burning Ground effect. So if 30 Oil Grenades go off on the same spot and get ignited, then there are 30 Burning Ground effects in the same exact spot and I go from 100+ fps to about 15 fps until the exact moment the Burning Ground expires. If there was a way to prevent so many Burning Ground effects from being shown when they overlap, that would make Oil Grenade and anything else that spawns Burning Ground feel much better to use