There was an article ages ago I read about the rewrite of C#'s Dictionary to the new generic one that went from being reliant on allocations in the older releases (C# 1.0 didn't have generics so iirc it behaved more like Java's) to using a generic struct array.

Doing so cut down the number of memory allocations to _3 allocations_ from something like _2 * N allocations_ (N being the number of elements in the map).

The improvement in performance was apparently staggering when it came to lessening the GC pressure. (Sadly I couldn't find it with a quick google).

https://github.com/microsoft/referencesource/blob/master/msc...