### 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.
''' this is never called from production code, it is here to be used when debugging as a 'complex print' '''
        if depth == 0:
            display.debug("DUMPING OBJECT ------------------------------------------------------")
        display.debug("%s- %s (%s, id=%s)" % (" " * depth, self.__class__.__name__, self, id(self)))
        if hasattr(self, '_parent') and self._parent:
            self._parent.dump_me(depth + 2)
            dep_chain = self._parent.get_dep_chain()
            if dep_chain:
                for dep in dep_chain:
                    dep.dump_me(depth + 2)
        if hasattr(self, '_play') and self._play:
            self._play.dump_me(depth + 2)
    def preprocess_data(self, ds):
        ''' infrequently used method to do some pre-processing of legacy terms '''
        return ds
    def load_data(self, ds, variable_manager=None, loader=None):