Too heavy build and slow loading.

I made simple room with 4 walls, bed few lights., few playmaker ascripts and some sounds.
Build is over 300 Mb’s!!!

MAIN QUESTION:

Did every asset imported makes build heavier or what?

What to do tonot have so heavy build, slow loading etc.?

The editor log when you make a build should list the size of everything included in the build.

tnx