The use of the M2 chip is the biggest change in the new 13-inch MacBook Pro from Apple’s 2020 version of the M1, but apparently it’s not the only one. YouTubers on the Max Tech and Created Tech channels (via MacRumors) ran speed tests on the 256GB version of the M2 MacBook Pro and found that the read and write speed of the SSD was 50% slower than the 256GB SSD in the M1 MacBook Pro.
The culprit seems to be the NAND flash configuration. The two YouTubers took a look at the new MacBook Pro and found that the 256GB versions only use a single 256GB NAND flash, while the M1 MacBook Pro uses a pair of 128GB flash. On drives with a large number of physical NAND chips, SSD controllers use a process called striping to read data from and write data to multiple physical chips at the same time. Use fewer chips and you can limit your peak performance.
Unfortunately for anyone who buys the cheapest version of the MacBook Pro, this problem is not unique to Apple. Many modern PC SSDs offer maximum nominal speed only at 1TB or 2TB capacities. Having higher-density NAND chips can increase your maximum capacity, allowing you to fit 4TB of storage on a drive that’s a little bigger than chewing gum. But the drop in speed at lower powers is one of the unfortunate side effects of increased density.
The larger 512GB and 1TB versions of the new MacBook Pro appear to offer SSD speeds similar to the M1 version, so if you’ve been aiming for more storage already, you won’t have to deal with these performance issues. It remains to be seen if the new MacBook Air with the M2 will have the same performance issues at 256GB, though it’s hard to imagine Apple shipping a 256GB Air laptop that performs worse than a similarly configured Pro laptop.