Although Boost.MultiIndex is a pretty old library — introduced in Boost 1.32, released in 2004 — I found it rather unsung and underestimated across the C++ community in comparison to other non-standard containers.

When writing some speed-critical code, I wanted to use Boost.Any as an attribute in a struct. This struct was small — 2 cache lines — and I knew that all the types that I would store in this Any would fit in 16bytes.

When changing the implementation of a time clock, I had to switch from a static method — think about a classic call to clock_gettime() for example — to a per-thread model. Long story short, it was about a constant TSC that was not so constant across different sockets.