The Lost Art of C Structure Packing
In some cases you can benefit by "struct of arrays" instead of "array of structs". This benefits packing, enables SIMD, and usually improves persistence speed too. Database people call this a "column store". So if you abstract it a little you can do per-column compression that is really hard to do with vanilla structs.<p>One thing I learned with Picasa (which is basically an in-memory database): if you're storing a lot of data in RAM, sometimes you should think of the data structures more as a database (with copy in/out, rather than reference). In multithreaded cases, this kind of approach unexpectedly gets you more parallelism and speed.