You pay 12 thousand more and get slower memory. Test revealed a weakness of the 1TB iPhone

Whoever pays extra for the largest storage at Apple logically expects the best. This is not the case with the iPhone 18 Pro Max. The terabyte version costs 55,990 CZK, 12,000 CZK more than the 512GB model, and according to a test by the Chinese channel HOMOLAB, for that money you get a slower type of memory. You won’t notice it during normal use. During longer writes, however, you will, and significantly.

Three bits, or four?

Most current phones use TLC memory, which stores three bits per cell. QLC memory fits four bits, so more data can be stored on the same chip, and manufacturing is cheaper. However, the cell must distinguish twice as many voltage levels. It’s like writing in smaller print on the same size paper. QLC is therefore slower for writing and has a shorter lifespan.

Fast only until supplies run out

The weakness is masked by a fast SLC cache. As long as it has free space, the iPhone writes at speeds of over 3,000 MB/s. On an empty phone, this is roughly 250 GB. After it fills up, it switches to a second buffer layer, which runs at an average of 578 MB/s, albeit with large fluctuations. When that also runs out, data is written directly to QLC. There, HOMOLAB measured an average of 79.4 MB/s and a drop to as low as 25.6 MB/s, which is less than many cheap microSD cards.

The fuller the phone, the worse the results

When the storage is 60% full, the fast cache shrinks to 58 GB. The second layer slows down to 396 MB/s, and direct writing to QLC averages 45 MB/s, dropping to as low as 1.1 MB/s at its worst. Random read performance is similar to TLC. The difference only becomes apparent when combining reading and writing, where TLC led by approximately 38% under light load.

Those it’s intended for will pay the price

For messages, web browsing, and casual photography, it doesn’t matter which type you have; the cache comfortably handles short bursts of data. The problem arises with long recordings in 4K or ProRes, transferring large files, or restoring from a backup. However, this is precisely why people buy the terabyte version. Apple does not specify the memory type in its specifications. According to earlier leaks, the 2TB version, priced at 73,990 CZK, also likely received QLC, and some 1TB units are reportedly appearing with Samsung’s TLC chips. Both remain unconfirmed for now.

Would you buy a phone with slower memory for greater capacity?

Source: Notebookcheck (HOMOLAB), AppleInsider, Mobilenet