Although Apple's latest flagships enjoy serious technological interest, recent independent laboratory tests have revealed a disturbing fact about the most expensive modifications on the market. It turns out that the iPhone 18 Pro and iPhone 18 Pro Max models with a capacity of 1TB and 2TB use a different type of flash memory compared to the more affordable versions, which leads to a significant drop in speed under heavier loads.
According to the technical analysis guys, the basic variants with 256GB and 512GB of memory rely on high-quality TLC (Triple-Level Cell) chips, in which each cell stores three bits of information. In contrast, the expensive modifications with 1TB and 2TB switch to QLC (Quad-Level Cell) technology, which holds four bits per cell. Although QLC memory allows for higher capacity at lower manufacturing costs for manufacturers, it suffers from lower endurance and drastically slower write speeds.
To mask this physical disadvantage, Apple uses a complex three-layer caching system, including a fast SLC cache and an intermediate TLC layer. With an empty drive, peak speeds exceed 3,000 MB/s. However, the problem arises when the buffer is exhausted during massive file transfers or prolonged high-resolution video recording. When the cache memory is full, the write speed directly to the QLC array drops to only about 79 MB/s, and when the drive is more than 60% full, it can drop to a critical 1.1 MB/s. In addition, there are also about 38% weaker results in 4K random reads compared to the 512GB version.
This compromise raises serious questions among the tech community, especially against the background of the premium price that buyers pay for the highest memory configurations. Although the difference will not be noticeable for everyday tasks such as browsing or chatting, the lack of premium memory in flagships costing thousands of euros remains a serious complaint about the pricing policy of the Cupertino technology giant.