Check what's subtracting FPS?

Hi! My game’s lagging in some moments and I want to know what’s the problem. I know that I can do that by using Unity Profiler but I haven’t got Unity PRO. Is it possible to do it by other way?

Without the profiler, its pretty rough, but you could try disabling scripts/game objects in your game one at a time and running the game to compare frame rates to find what code is taking up most the processing. Just to throw out a few things that might cause substantial lag include using Object.Find in update(Never use Find in general), searching large arrays every frame, Instantiating and Destroying large amounts of objects (Garbage collection sucks in Unity), Having too high poly meshes in your scene, not using Occlusion culling, not baking your light maps, having too many point lights, having too many draw calls, ect.