Bytes have a location
A raw output-size reduction may save network transfer, cache storage or disk space. It may save nothing when another layer already compresses the payload or when the artifact is generated once and reused indefinitely.
Processing time also has a location. Work on every dynamic request differs from work performed once during a deployment or at a CDN edge.
Ask for the incremental cost
Compare each step to the next realistic alternative: extra microseconds per kilobyte saved, extra build time per artifact, or extra memory per concurrent request. That framing is more useful than ranking one column in isolation.