Game lag while testing, export work's fine. Explanation?[SOLVED]

Hello everyone

I am working on a project which get's really laggy while testing both in normal and debugger mode, but when I run the export it work's fine.

FPS while testing is 10 FPS or less while in the export it is 20+ FPS(yeah I know, not the best speed still).

Why is that? How could I boost performance?

Thank you!

Best regards,

Martin Starešinčić