Android Build Game Lagging Only at the very First Launch

I have a complete game going to be published, but there is a problem with android build (IOS as well). When I install the game on the device for the very first time, it is quite lagging, fps often drops below 15. But on the second or third launch everything is fine, stable 50-60 fps. I am using IronSource SDK for ads and monitoring and I blame it, but might be mistaken. Did anybody encounter same problem and have any idea how to solve it?

Hi! Did you find a solution? I have the same problem,Hi! Did you find a solution? I have the same problem