Game frame drop breaking game

Hello,
whenever i play test my game it sometimes starts to do a major frame drop and my characters glitch through the obstacles.
i’m not sure how to fix it, or how to format this question, :P.
I’ve tried making the falling blocks delete themselves after disappearing on the screen.

Any help would be appreciated,
Thanks

I think you should profile your game first to locate underlying issues.

Frame drop may be caused by different reasons, e.g. frequent garbage collection, rendering large amount of triangles or particles. As a result, there is no one certain solution for addressing frame drop issue. To figure out the real cause for your own app is the only way. The KEY is to debug into your app with Unity profiler.

It is recommended to read Unity Profiler section in best practices.

A low frame rate should only have an effect on your collision detection if you somehow move your Rigidbody in Update() instead of FixedUpdate(). Update() is called exactly once per frame and therefore less frequent when the frame rate is low. FixedUpdate() is called with a fixed time interval independent of the frame rate. How exactly is your character moved?