Comment by timschmidt

> which means that now, they need to make a conversion, which is obviously slower than doing nothing.

One would think. But since caches have grown so large, and memory speed and latency haven't scaled with compute, so long as the conversion fits in the cache and is operating on data already in the cache from previous operations, which admittedly takes some care, there's often an embarrassing amount of compute sitting idle waiting for the next response from memory. So if your workload is memory or disk or network bound, conversions can oftentimes be "free" in terms of wall clock time. At the cost of slightly more wattage burnt by the CPU(s). Much depends on the size and complexity of the data structure.