I've always wondered at the performance of Mono relative to the Real C#, but I suspect that Microsoft has language in the license to prevent such benchmarks (or something)...
Some benchmarks are in the Game. Looking over the benchmarks, I realized that I shouldn't be comparing Mono to the Real C# since I wouldn't ever run Mono on Windows. I'd only ever run it on Linux, so, if you're running a Linux stack, Mono should be compared to its colleagues in the Linux space.
Mono vs Java: http://benchmarksgame.alioth.debian.org/u64q/csharp.php
Mono vs Go : http://benchmarksgame.alioth.debian.org/u64q/benchmark.php?test=all&lang=csharp&lang2=go
Mono vs Rust: http://benchmarksgame.alioth.debian.org/u64q/benchmark.php?test=all&lang=csharp&lang2=rust
There are a bunch of notes trying to make it very explicit that this test is supposed to isolate the garbage collector's performance. So they discourage lazy evaluation on the grounds that it might not produce the kind of allocation pattern the test is supposed to generate, and there's that bold admonition against memory management hacks, and all of that.
I'm sure there's still plenty room for gaming the system, but looking at the actual C# & Java implementations for the test reveal that by-and-large they really are roughly equivalent. In particular, the C# doesn't resort to any obvious dirty trick like declaring the tree node datatype as a struct rather than a class. The upshot being, what that particularly test suggests is something that probably shouldn't come as much surprise: Mono's gc, while good, isn't quite as performant as HotSpot's.
Mono's package appears to lag behind their code releases by a significant amount.
So while you can download and build the source for 3.10 right now you can not download the packaged mdk's as easily. At least it's not trivial to find them anyway. I'm not sure of why this is.
Some benchmarks are in the Game. Looking over the benchmarks, I realized that I shouldn't be comparing Mono to the Real C# since I wouldn't ever run Mono on Windows. I'd only ever run it on Linux, so, if you're running a Linux stack, Mono should be compared to its colleagues in the Linux space.