A simple 2D unity game facing Jerks/Lags

A simple 2D game that doesn't have any high graphics and should run smoothly on mobiles but isn't working as supposed to. Everything was working fine until i had to switch scripting backend in unity player settings from Mono to IL2CPP as i had to upload it on google play store. After changing scripting backend game starts showing lags no matter on what mobile i play.

Then I inserted below mentioned command in Awake method

Application.targetFrameRate = 60;

Before giving this command it was having lag on all android devices but now some of the devices are running this app without any lag and very smoothly but most of them are still lagging. And i am unable to figure out that what should i do now to get rid of this lag as there was no problem before changing scripting backend from mono to IL2CPP...