DeepSeek Prefix Cache Hacks: Cut Agent Token Costs by 90% to $0.005/Task
BodybuilderLost328 · reddit · 2026-08-12
The author shares deep optimization experiences using DeepSeek's prefix cache for their browser agent, Retriever AI, successfully cutting token costs by 90% to under $0.005 per task, enabling an ad-supported free agent.
Key practices to increase the cache hit rate from 24% to 87% include:
- Stable Prefix: Place stable prompt segments before volatile ones.
- Beware of Invalidation: JSON mode silently breaks the cache; stray timestamps invalidate subsequent content; tabs vs. spaces affect token usage.
- Minimize Variance: Limit conditionals/variables in prompts and monitor variants strictly.
- State Storage: Leverage the model's verbose thoughts to store previous states, removing historical page tree observations.
- Architecture: A text-only architecture turning web pages into reusable semantic trees is ideal for aggressive caching.
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