Lag when loading ads in background (banner/interstitial/video ads - banner and interstitial)

Hi,

All my games lag when I'm loading ads.

In my native apps, it's ok.

But on Unity, the frame rate drop down during few minutes...

Is there anybody who know how to handle this issue ?

(tested with chartboost, admob, iAd, unity ads).

Thanks for your help !

Best regards,

AB