Whenever i load scene 2 after completing scene 1 there is a tremendous drop in fps it is showing only 0.1 fps

i'm currently building a low poly open world game for android , in my game there are 4 different worlds Each world is working fine if i'm playing it individually in unity editor .After building all the scenes along with main menu and world selection scenes the problem begins.The problem is if i'm playing the game after completing world selection and main menu scenes for the first time it is working perfect ,but when i switch between scenes I.e moving from lvl 1 to lvl 2 , Frame rate is dropping more like it came down to .1fps BUT LVL 1 worked fine Even after going to lvl 1 it starts lags. If i exit the game and start it again there is no frame drops after completing level 1 and going to lvl 2 the frames started dropping , but all the scenes are working perfectly if i play it individually .Can anyone help me in soving this issues. Thank you

I have a doubt wheter all the objects in the scene are destroyed or not, and i did'nt use don't destroy command on any one of the game object. Since the worlds are little big i need to provide any loading time???or a memory LEAK???