I have pop up's that say they are helping my phone. They are followed by ads. Make them stop.

I can't figure out what app is causing these screens popping up interrupting everything saying either 'Optimizing Battery', 'Speeding up Your Phone', 'Speeding your Internet' and 'Cooling your phone'.
When I close them, they are followed up by an ad, half the time noisy.
I can't figure out what is on my phone that is causing it.
Please help.

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