Instead of

const Thing = struct {
   checksum: u128,
   number: u32,
   flag: u8,
};

use

const SoA = struct {
   checksum: []u128
   number: []u32,
   flag: []u8,
};

in certain circumstances:

• Reduced memory usage due to amortized padding. As flag is a byte, it requires some padding to align with larger fields like checksum.
• Better memory bandwidth utilization for batched code. If a loop needs to process all things, but the processing doesn't require all fields (at least for the majority of objects), then an array-based representation reduces the amount of data that needs to be loaded.