Creating 2D water without dropping the frame rate.

I've got this game I'm working on. And in it you can destroy the ground, and cause water to flow and spread to other areas. Similar to Minecraft's water, but it's in 2D. The problem I'm facing is even though I'm using things like object pooling, the frame still drops pretty quick once more water is created and spreads throughout the area. I'm wondering if there's something I can do to make sure the frame rate stays smooth with all the new water gameObjects. See the video below for a more visual example of my game and what I'm talking about, any help or suggestions would be much appreciated.