[drzaiusx11]

Mono was in a usable state on Linux for literal decades before becoming official and integrated into what is core today, that is unless you needed windows forms, which much like MSFT UI frameworks today had multiple failed attempts spanning those same decades...

[seabrookmx]

Only if you didn't care about performance.

We attempted a move to mono for backend web services maybe 3 years before .NET Core released, and it was a complete no-go. 10x reduction in performance on the same hardware.

This wasn't specific to our workload either. I was big into the game Terraria at the time, and I saw similarly poor performance when running it's game server under mono vs .NET 4.x

While some of the mono toolchain was integrated into .NET Core, CoreCLR was a rewrite and immediately solved this problem.

[drzaiusx11]

Great context, thanks! I knew it worked (I closely followed mono development at the time) but I didn't have a windows license/windows machines at the time it was ongoing to compare it to. 4x is pretty bad, any ideas what went wrong? Lack of jit maybe? I forget the exact architecture of mono at that time, being like 20 years ago...

[seabrookmx]

It did have a JIT, it just wasn't a very performant one. I recall the GC implementation also being quite slow. GC is an area where .NET is still making strides.. we got a new collector in .NET 10.