The Zhihu author "苏迟但到" conducted a test with 20,000 trials lasting 3 days, covering DeepSeek, Kimi, Zhipu GLM, MiniMax, and OpenAI models called through OpenRouter. The method was to send 27 random requests to each model every 40 minutes, and then send the same content again after 1 minute to 720 minutes (up to 12 hours), recording whether the cache still hit.
The results showed that DeepSeek's cache hit rate always remained 100% whether during working hours or non-working hours, with no obvious invalidation even at an interval of 12 hours. MiniMax ranked second, with a hit rate of about 90% during non-working hours and dropping to about 70% during working hours; Kimi and OpenAI were in the middle; GLM was the weakest, with a hit rate of about 80% after 2 minutes, dropping to 50% at 3 minutes, and only 25% left at 5 minutes, and almost no cache survival beyond 15 minutes was observed.
The author gave two explanations for GLM's weaker performance: first, KV Cache relies more on VRAM and lacks the ability to persist to lower-cost storage media, causing frequent cache eviction; second, the actual request volume is too large, exceeding cacheable capacity and accelerating the invalidation of old caches. Both explanations are currently only speculation.
It must be emphasized that this set of data comes from personal testing and is a source_claim; and how long DeepSeek's official cache hit rate advantage can last is something the article itself also considers worth pondering.