Simple 3D Model make my game LAG ( It will be kindly if someone or somebody answer)

Hello! good am/pm, I'm having some a bit of problem in UNITY because when i try to import or place my SIMPLE LOW DESIGN 3D MODEL in my game project my game lag and when i check or view the stats the FPS/Frame Per Second is low and i already tried to search on google but i got no results of answer! Is there a way it will be able to be fix? it would be kindly if somebody or someone answered! Thank you.