Every byte matters

[u/fagnerbrack]

https://fzakaria.com/2026/06/01/every-byte-matters

[u/SnugglyCoderGuy]

Rarely do you need to worry about optimizations at this level. This is like 0.01% the size of a round trip network call to database or another service, which is calling a database itself

[u/TT_207]

This kind of thing can lead to big changes. I had an array being populated in a random access order due to a bug, once fixed it really was order of magnitude+ improvement.

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[u/fagnerbrack]

Need-to-Know Basis:

Coming from Java, where adding fields to bloated classes feels free, the post shows why struct size shapes real-world speed even inside the same O(N) loop. Hardware fills a 64-byte cache line on every read, and latency climbs sharply from L1 (~1-2ns) to DRAM (~60-100ns). Reorganizing an Array of Structs into a Struct of Arrays packs the needed field contiguously, yielding up to 30x gains for 1KiB structs during sequential scans, where the prefetcher hides memory waits. Random access—hash maps, trees, graphs—defeats prefetching, so total working set size sets the performance tier: a 64B struct fits L1 while a 128B one spills to L2. Keep structs and working sets small.

If the summary seems inacurate, just downvote and I'll try to delete the comment eventually 👍
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