❯ A third-party test finds sustained-write slowdowns in a 1TB iPhone 18 Pro Max under extreme loads

Test resultThird-party channel Homolab tested a 1TB iPhone 18 Pro Max and reported a sharp slowdown in its QLC storage after prolonged heavy writes. In its comparison with a 512GB TLC device, some read results were close; the larger gap appeared after write caches were exhausted.

Cache effectQLC holds more data per cell and helps raise capacity, while fast caching handles short bursts. Coverage of the test cites later-stage average writes near 79.4MB/s, with some phases lower. This is a particular device under stress, not proof that every capacity, batch or routine recording session behaves the same way.

Buyer relevancePeople recording long, high-bitrate videos or moving large files may care about sustained write speed more than advertised capacity. Photos, app installs and shorter clips usually finish within cached operation; an extreme test should not be turned into a claim of universal lag.

▪ SIGNALIf the large-capacity trade-off appears only after caches run out, buyers should compare it with their own continuous-write workload.