In my experience (which isn't data) the correlation is weak at best, I know people I consider much smarter than me who read slower (my boss for example, he has advanced degrees in industrial chemistry and is ridiculously smart)

That and people over-estimate my intelligence because I know about lots of random things, they think I'm smart because of that but they could have done exactly the same thing if they'd chosen to which feeds nicely into nature vs nurture I guess.

I got hooked on books and my mum fed that addiction, that they didn't is the only difference.

It helps that the perception of computer programmers is that we are geeky but do something that is incredibly difficult (when I know the reality is except for certain domains, you really don't need much math beyond arithmetic and the rest is conscientious attention to detail and explaining the problem simply to a really high speed idiot).