Hacker News AIT2·68 pts
- Harness caching mechanisms dictate input token computation ratios; a drop from 97% to 92% cached tokens increases prefill workload by ~2.7x.
- Prompt cache misses roughly double request energy consumption, reaching up to 2.5x on models like GLM-5.3.
- In sessions exceeding 128k tokens, re-reading more than half the prompt costs as much prefill compute as ~600 normal short turns.
- Most cache breaks stem from harnesses improperly editing previously sent context, forcing full recomputation from the first difference.