Quoting @jeff.bezanson’s answer from Julia vs R vs Python - #90 by jeff.bezanson :
This is an interesting point, and I agree with it — I like to think Julia has many selling points, and we should trumpet all of them. However, in practice, it is very hard to get anybody to adopt a new language. Performance is one of the few or only things that gets people’s attention. The other big thing, of course, is library support, but any new language will always have fewer libraries than existing languages, so that can’t be an initial reason to adopt a new language.
Anyway, try convincing somebody that language X has a nicer syntax or is easier to use than language Y. They won’t believe you, and even if they do it’s not really compelling enough to go through the difficulty of switching. Or try the default pitch of most research languages, which is that they will catch more errors at compile time. Well, it’s quite evident that a large percentage of programmers simply don’t care about that. But if you can take something that runs overnight and make it run in a minute, you have a real painkiller. If somebody doesn’t have any code that takes a while to run, getting them to switch languages might be impossible.
Performance is actually special. It’s not just another feature. All languages are Turing-complete so you can write anything in any of them. Performance is one of the only meaningful ways you can hit a wall with a language and not be able to do something.