DNS gets really slow after using for some time

So I enjoy using your DNS service but after a while of using it it slows down like really slow and I have to reset the DNS for it to go fast again. By the way I’m using Android Pie so what I do is I set it to off and then I turn it back to private DNS and then it goes back to normal speed again. This also happens when I use warp as well, it gets very unstable when I’m trying to load a website or something and takes a long time but when I disconnect and reconnect it corrects it. I’m not sure what’s going on here unless it’s a caching issue or something but I would like to be able to stay connected to it at it’s normal high speeds without having to disconnect and reconnect every once in awhile.