The query cache was behind a single lock. Thus while fast, it serialized all DB operations. And the more CPUs you have the slower the performance. Especially since any write has to go through the cache and invalidate all affected queries.
It was meant to accelerate PHP code in the 90s with single core CPUs. It was never designed to be scalable and in-development (back then) versions had already disabled it, which gave me the idea that it was something to try.
It was meant to accelerate PHP code in the 90s with single core CPUs. It was never designed to be scalable and in-development (back then) versions had already disabled it, which gave me the idea that it was something to try.