I have an assembly file which is 398mb(!!), don't know exactly why. I have deleted all the components with no effect.
What I've noticed is that there is something embedded to this file. You can see that in that picture attached.
I suppose this is the cause of such big size. However I can't find how to delete this embedding.
I should have searched before posting.
Here is the answer:
Thanks to author of that post!
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