EAGLE-3 Speculative Decoding in Production

Speculative decoding pairs a fast draft model with the target model. The draft proposes K tokens; the target verifies in a single forward; accepted tokens are free. In 2026, EAGLE-3 is the production-grade variant — it trains a draft head on the target model's hidden states rather than on raw tokens, pushing acceptance rate alpha into the 0.6-0.8 band on general chat. The right question is not "how fast is the draft" but "what is alpha on my traffic?" If alpha drops below ~0.55, speculative decoding is net negative at high concurrency because every rejected draft costs a second target forward pass. This lesson teaches you to measure alpha first and flip the flag second.