[Feature]: _fireSelectionEvents easy performance win

[SLKnutson]

CheckList

• I agree to follow this project's Code of Conduct
• I have read and followed the Contributing Guide
• I have searched and referenced existing issues, feature requests and discussions
• I am filing a FEATURE request.

Description

While profiling, I noticed there is an easy performance win within _fireSelectionEvents. This function shows up in profiling when you are selecting/deselecting a large number of objects (low 1000s). Right now, it determines what is added and what is removed by looping each array and checking if the object exists in the other array. If the existence check was against a set instead of searching the whole list, the performance would be improved, especially when you have large numbers of objects.

I don't have time to do a PR, but I think it would look something like this:

let somethingChanged = false,
  invalidate = false;
const objects = this.getActiveObjects(),
  added: FabricObject[] = [],
  removed: FabricObject[] = [];
const objectsSet = new Set(objects);
const oldObjectsSet = new Set(oldObjects);

oldObjects.forEach((target) => {
  if (!objectsSet.has(target)) {
    somethingChanged = true;
    target.fire('deselected', {
      e,
      target,
    });
    removed.push(target);
  }
});

objects.forEach((target) => {
  if (!oldObjectsSet.has(target)) {
    somethingChanged = true;
    target.fire('selected', {
      e,
      target,
    });
    added.push(target);
  }
});

Current State

Works, but slow for large numbers of objects.
Thanks!

Additional Context

No response

[ShaMan123]

I don't have time to do a PR, but I think it would look something like this:

Hope you find the time, seems good

[proke03]

In my opinion, it seems to be an invalid method due to the overhead caused by the operation new Set(arr).