The fruity cargo cult’s most expensive 1TB iPhone 18 Pro Max can see storage speeds collapse to a magnificent 1.1MB/s when its QLC NAND finally runs out of tricks.
According to Tom’s Hardware tests by Chinese hardware channel Homolab, Jobs’ Mob’s premium shiny toy performs reasonably well until sustained writes exhaust the caches hiding what the underlying flash can do.
The 1TB iPhone 18 Pro Max reportedly uses QLC NAND, which stores four bits per cell. This gives Apple greater density and presumably leaves more room in Cupertino’s margins, but it comes with weaker sustained write performance than TLC NAND.
Homolab compared the 1TB QLC-equipped iPhone 18 Pro Max with a 512GB iPhone 18 Pro using TLC flash. In 4K read tests, the difference was small. In a low-queue-depth mixed workload, though, the QLC model scored 8,168 against 11,285 for the TLC version, leaving the more expensive handset about 38 per cent slower.
Under heavier workloads, the gap narrowed to 12 per cent, meaning the average fanboy checking social media is unlikely to notice anything untoward while admiring the reassuring Apple logo. The fun begins when large amounts of data are written continuously.
Initially the phone hides behind an SLC cache capable of about 3,000MB/s. When that fills, a secondary buffer takes over at roughly 578MB/s. Once both safety nets disappear, the iPhone has to write directly to the QLC NAND Apple actually sold you.
Speeds then average about 79.4MB/s and can fall to 25.6MB/s. For a supposedly premium device, that is already entering territory where ancient storage hardware can point and laugh.
It gets worse as the phone fills. At 60 per cent capacity, Homolab found that the available SLC cache shrank from about 250GB to just 58GB. The secondary buffer dropped to roughly 396MB/s, while direct QLC writes averaged around 45MB/s.
At its worst, direct write speed collapsed to 1.1MB/s, which is slower than an asthmatic ant with a heavy load of shopping. Many mechanical hard drives can do much better for a tenth of the price.
The benchmark is deliberately brutal, and ordinary users sending messages or browsing the web are unlikely to encounter the worst-case behaviour. Apple puts the word Pro on the box and markets these things at people shooting large video files, shifting hefty projects and recording ProRes footage. Those are precisely the workloads most likely to expose sustained-write weaknesses.
QLC itself is not some sinister Cupertino invention. Manufacturers use it because it packs more capacity into the same amount of silicon. Fast caches disguise its slower native write speeds during normal use. Apple’s contribution is charging flagship money for the privilege and relying on most members of the iCult never writing enough data at once to discover what is underneath.
