[Debugger Perf] Conditional BP evaluation on Linux is SLOW

[chuckries]

Environment data

dotnet --info output:
VS Code version:
C# Extension version: 1.7.0

I ran the following code on Linux:

        static void Main(string[] args)
        {
            var sw = new System.Diagnostics.Stopwatch();
            sw.Start();
            for (int i = 0; i < 100; i++)
            {
                var elapsed = sw.Elapsed;
                // Do Something with i
                int j = i; // bp here on i == 50
                j++;
            }
        }

with a conditional breakpoint set on the specified line. The condition was i == 50.

When the breakpoint is finally hit, the value of elapsed is 5.7 seconds. This seems incredibly slow. On my Windows machine (granted it's a different machine), the value of elapsed is 0.35 seconds.

[amshtemp]

Same can be said about Mac.
It is extremely slow to the point it has become unbearable.

[gregg-miskelly]

There are two causes --

1. There was a bug in the vsdbg event processing that wasted, on average, 50ms per hit. I fixed this.
2. Stack walk performance in the CLR debugging services is MUCH worse in Linux. I opened https://github.com/dotnet/coreclr/issues/22315 to track this.