How do I prevent Google Search from spawning instances?

I love using the white Google search bar at the top of my home screen, but I only recently discovered that it spawns a new instance for every search I do. My phone was slowing down, and I suddenly noticed I had dozens of past searches in my app switcher. I went through and closed them all, and now my phone is happy again.

Can I have all searches share one instance? Or do I have to clean them up periodically myself? :(