After each optimize run, the Optimization tab lists every file with before/after sizes. Here's how to use it.
What the columns mean
Before is the original bytes; After is what we actually serve; Saved is the difference. A dash means the file was copied unchanged (already optimal or a type we don't transform).
What to look for
Big files with small savings are your opportunities: an uncompressed BMP or a 4 MB hero PNG tells you to re-export the source properly — the optimizer can only do so much. Files showing "copied" for code types usually mean a syntax issue prevented safe minification; check the file.