> Why is that an achievement? There are tables in the paper comparing its speed to other implementations. This is more than an order of magnitude faster than t

> Why is that an achievement? There are tables in the paper comparing its speed to other implementations. This is more than an order of magnitude faster than the implementation used in Chrome, and for small data more than twice as fast as their previous AVX2 based implementation (https://arxiv.org/abs/1704.00605 https://arxiv.org/abs/1704.00605). The paper even notes that in some cases, for large inputs, it's decoding base64 faster than you could memcpy the data for the simple reason that it needs only write 6/8ths of the bytes. In their tests, it's only when the data fits in the tiny L1 cache that memcpy is consistently somewhat faster (44 GB/s vs 42 GB/s). So this is not only fast when you have to wait for a slow memory access, but when the loads hit other caches. Or are you asking in more of a rhetorical sense? Like, why hasn't this been achieved before, that it's obvious or something? AVX-512 is only some 3 years old and base64 is only one of many problems that could benefit from vectorized processing.