I use the 2018 MacBook Air, 1.6ghz 16gb ram as a developer / development manager and it is faster than the 2015 pro it replaced with similar specs. The only thing I've seen it slow down on is compiling Rust, but I think that's just because that operation is slow.
Jetbrains IDEs works fine, not sure about XCode haven't done much with this machine yet in Mac Development.