enforce()?

[bearophile]

Steven Schveighoffer:
> Isn't everyone always  
> saying around here how cheap memory is these days? ;)

RAM is cheap, but the CPU doesn't used RAM, it mostly uses L1 cache (and a bit L2/L3 caches too), and they cost a lot :-) The more space your data structure uses, the less you can fit in the cache. Today cache effects are important for the code performance.

This is a nice example, shows how reducing the size of the data structure and changing its arrangement (the original was a normal tree, transversed for each pixel) can improve the code performance by something like one order of magnitude for ray-tracing:
http://www.cs.utah.edu/~bes/papers/fastRT/paper-node12.html

Bye,
bearophile