Slow Teardown for Realm

[sync-by-unito]

While testing issues with Jest, I noticed that the teardown for Realm is quite slow. A simple open and close will take about 10 seconds before the process finally closes.
Here is a sample in Jest:

describe('realm', () => {
  it('can open without crashing', async () => {
    const realm = await Realm.open({schema:[TodoList, TodoItem], inMemory:true})
    realm.close()
    expect(1).toEqual(1)
  })
})

Here is an example in Node:

const Realm = require("realm");

let realm = new Realm( { schema: [
    {
        name: "Simple",
        properties: {
            v: "string",
        }
    }
]});
realm.write(() => {
    realm.create("Simple", { v: "Hello" });
});
realm.close();

We should see if it's possible to make the teardown instantaneous.