Comment by gmrple

Next, if you really want to time something fast you should probably know about cache. In a modern computer there are levels of memory. For now we’ll say we have 3 levels: cache, ram, and a hard drive. Cache is small but very fast, it is the closest level to the CPU. RAM is bigger but slower and the hard drive is much much slower. Because the cache is small the computer has to pick what’s in it. At program load the cache will be full of information related to whatever was running before you. After you run you will have left some information in the cache which will not need to be fetched from slower levels of memory. Unless your usecase is to run your test code repeatedly very quickly, you should be wary of timing multiple calls in fast sequence as the later calls will execute faster due to the cache being primed to execute your code.