> I should have made it more clear: I'm interested in how fast it can be.
The answer you are looking for is: much slower than .NET core.
The "being good at multiprocessing" of the BEAM VM people are bringing up is not about raw speed at it: it is about giving you the tools to actually being able to do multiprocessing in a sensible, stable manner.
For instance, what happens if a bug in your program blocks threads for a long time in .NET core? What if one thread crashes? Do you have any guarantees that one thread cannot affect others in any way? Etc.
Some developers think that giving up raw performance for guarantees in these areas makes sense. Other developers think they can deal with those issues without nice guarantees from the platform and thus prefer the speed. There's no definitely right answer...
Another consideration: Phoenix PubSub makes it simple and performant to add more servers. So if one (say) chat app server can provide acceptable performance for N users, you can serve N more users by adding another node.
The answer you are looking for is: much slower than .NET core.
The "being good at multiprocessing" of the BEAM VM people are bringing up is not about raw speed at it: it is about giving you the tools to actually being able to do multiprocessing in a sensible, stable manner.
For instance, what happens if a bug in your program blocks threads for a long time in .NET core? What if one thread crashes? Do you have any guarantees that one thread cannot affect others in any way? Etc.
Some developers think that giving up raw performance for guarantees in these areas makes sense. Other developers think they can deal with those issues without nice guarantees from the platform and thus prefer the speed. There's no definitely right answer...