Every P-256 or X25519 ECDH operation uses a new ephemeral single-use key breaking which is about as hard as brute forcing AES-128. Global bitcoin hash rate is something like 90 bits per year. People think NSA doesn't have more hardware than all the bitcoin miners together. If they can break 128 bit security, they can't break it for every roundtrip in a Signal chat. I don't know what they would even use the capability to do. I don't think they need brute force to forge a Microsoft or Apple signature - easier to steal it. But it would be something high value that would be broadly useful, not a single message.
and more importantly, any operation that needs that much compute power can be more efficiently solved by passing around a couple billion dollars of bribes
