LIKE cannot use an index and everyone knows it. The mapping, the analyzers that decide what matching means, the indexing pipeline, and the drift it introduces.
A single DELETE removing two million rows holds locks for the duration, generates one enormous transaction in the binary log, and a replica applying it single-threadedly falls behind…
OPcache keeps compiled bytecode in shared memory, which is empty after every restart — so the first requests following a deploy or an FPM reload each pay full…
gzip on compresses every response as it is sent, which for a static bundle means doing the same CPU work for every visitor to produce an identical result.…