Does Google Admob make the performance of Unity3d slow?

Question

Firstly I built my app without admob on Android and Ios both and the speed of performance was good enough to use. Now, I imported the Admob plugin to my app and simply show the banner at the bottom but the performance is much slow and cannot see it anymore.

Does Admob heavily affect the unity performance?

Is there anyway to avoid this slow Admob?

Below is my admob banner code.

// using GoogleMobileAds.Api; private BannerView bannerView; private InterstitialAd interstitialAd;

void RequestBannerAd() { bannerView = new BannerView(adUnitId, AdSize.SmartBanner, AdPosition.Bottom); AdRequest request = new AdRequest.Builder().Build(); bannerView.LoadAd(request); }