as far as I remember some users said that AdMob banners are slowing down Crosswalk apps
Yes, I am using Crosswalk. I'll try building for Cordova Android (using Intel XDK).
EDIT: Made a huge difference. No more lag and the app is smaller too.
Develop games in your browser. Powerful, performant & highly capable.
My app (android game) works fine at ~60fps but adding AdMob makes it lag. Is this just me?