Japanese puts the verb at the end of the sentence. I built an all-local streaming speech translator and measured what that costs: early English-to-Japanese guesses share almost nothing with the final translation.

Scope note, first paragraph as promised: read speech (FLEURS test set) only, greedy decoding everywhere, Whisper-small plus two small MT backends (opus-mt + Qwen2.5-1.5B), no human listening test, no LLM judge. The headline asymmetry is measured on reference transcripts, so ASR error is excluded by construction.

Why word order is a latency problem

English is SVO: "The dog ate the food." Japanese is SOV: the verb comes last. A simultaneous translator hearing English must either guess the verb early (and flicker when wrong) or wait for it (and lag). Textbook linguistics; I wanted a number.…