### Summary

Executing a playbook with many hosts, there is massive overhead in checking whether the hosts list is a pattern, see for yourself on this callgrind graph:

![grafik](https://user-images.githubusercontent.com/3154871/111359016-4a4bf480-868b-11eb-8c8f-55b6a6a10bd7.png)

https://github.com/ansible/ansible/blob/da60525610a384bb04833b1c6429d9db6a87ef64/lib/ansible/vars/manager.py#L490

That check has quadratic runtime with the number of hosts - with a lot of hosts, commenting that check out reduces runtime manyfold.

### Issue Type

Bug Report

### Component Name

variable manager

### Ansible Version

2.10.5, devel

### OS / Environment

Ubuntu

### Steps to Reproduce

```yaml
- hosts: localhost
  tasks:
    - set_fact:
        extra_tasks: true # compute it
        hosts: "{{ [an, array, with, 5100, computed, hosts] }}"

- hosts: "{{ hostvars.localhost.hosts }}"
  vars:
    extra_tasks: "{{ hostvars.localhost.do_extra_tasks }}"
  tasks:
   # some more tasks here
    - name: Execute extra tasks
      command: /bin/true # example
      when: extra_tasks
```

### Expected Results

Execute in tens of seconds.

### Actual Results

Take over 5 minutes to execute.
while True:
        try:
            result = strategy._final_q.get()
            if isinstance(result, StrategySentinel):
                break
            elif isinstance(result, CallbackSend):
                for arg in result.args:
                    if isinstance(arg, TaskResult):
                        strategy.normalize_task_result(arg)
                        break
                strategy._tqm.send_callback(result.method_name, *result.args, **result.kwargs)
            elif isinstance(result, TaskResult):
                strategy.normalize_task_result(result)
                with strategy._results_lock:
                    
                    
                    
                    if 'listen' in result._task_fields:
                        strategy._handler_results.append(result)
                    else:
                        strategy._results.append(result)
            else:
                display.warning('Received an invalid object (%s) in the result queue: %r' % (type(result), result))
        except (IOError, EOFError):
            break
        except Queue.Empty:
            pass
def debug_closure(func):