No. Most encoders/decoders need assembly to get last drop of performance. Most of the times it comes down to when you give up. The team here was quite relentless to build a usable AV1 decoder. A few years ago this was a pipe dream and jbk and team have done a tremendous job.

I really can't see how you read anything else that "it's very optimized" in my message, tbh.

In addition to other noting that decoders and encoders almost all have an enormous amount of hand optimized code because they are literally the most demanding applications most people run (which is why most codecs today are hardware accelerated and they are used in almost all CPU benchmarks) 186k LOC (given that it's assembler which is nearly always "vertical code") is also relatively small for decoders.

People don't really get how complex video codecs are.

It's not they're writing a library full of assembly for the sake of it. Reading the readme, one can discover they have dedicated optimised implementations for a large range of processors, which in turns means there's a lot of assembly involved