Short-lived virtual threads are 1000x slower to create when run in Debug

We are looking at replacing our overly complex multithreading task system with virtual threads in our game engine. Unfortunately, this issue makes short-lived virtual threads more or less useless for us as a replacement for pooled executors, as we cannot achieve realtime speeds in Debug using them.

## Steps to reproduce

```Java
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicInteger;

public class VirtualThreadTest {
public static void main(String[] args) {

while(true) {
test();
}
}

private static void test() {

AtomicInteger integer = new AtomicInteger();

ThreadFactory factory = Thread.ofVirtual().factory();
//ThreadFactory factory = Thread.ofPlatform().factory();

int levels = 23;

runThread(levels, factory, integer);

long startTime = System.nanoTime();

int limit = (2 << levels) - 1;

int count;

do {

try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}

count = integer.get();

long timeTaken = System.nanoTime() - startTime;
System.out.println(count + " (" + 1_000_000_000f * count / timeTaken + " threads per second)");
}while(count < limit);
}

private static void runThread(int level, ThreadFactory factory, AtomicInteger integer) {
integer.getAndAdd(1);
if(level > 0) {
factory.newThread(() -> runThread(level-1, factory, integer)).start();
factory.newThread(() -> runThread(level-1, factory, integer)).start();
}
}
}
```

## Results

- In Run mode: 1.2249853E7 threads per second
- In Debug mode: 14427.094 threads per second
- Note that the exact numbers here depends on the CPU being used; the point is that the Debug speed should be as close to the Run speed as possible.

## VIsualVM sampling
Here a VisualVM screenshot of Eclipse while the test program above was running:


It would seem that Eclipse is bottlenecking the application by not being able to process all the threads being created fast enough. This theory seems plausible, as in Run mode I get 100% CPU load from the test program, while in Debug I only get 20% CPU load from the program and 100% load on one CPU core from Eclipse.

## Additional info

- Eclipse IDE Version : Version: 2025-03 (4.35) Build id: I20250117-1800 (completely fresh install in a new workspace)
- OS: Windows 10 64-bit