I recently had a look at how Swift is doing in the benchmark game compared to Java: https://benchmarksgame-team.pages.debian.net/benchmarksgame/fastest/swift.html
It seems striking that in the three last benchmarks k-nucleotide, regex-redux, binary-trees the solution written in Swift is slower by a factor 4 till 7. This is striking as Swift in some benchmarks displayed there is performing sligtly better or a lot better than Java and for those three benchmarks it is eye-catching that they are implemented with multiple threads. The Java solution uses Java's Executors which is their thread pool implementation and Swift uses Grand Central Dispatch.
So at first sight it seems like Dispatch is a lot less efficient than Java's Executors. I wanted to ask whether Dispatch being relatively inefficient is a known issue and if so whether there are any plans to do something about it.
Also, I would like to ask whether there is some alternative to using Dispatch.