On large recordsets I got some severe performance issues while browsing through an inherits relation.
For example I have a batch process exporting a csv file with products variants:

I have to export 50.000 products.

If I do :
`variant.categ_id` It takes a very long time to get the result.

If I do:
`variant.product_tmpl_id.categ_id` The result is immediate

The problem is that the global perfomance of the application is impacted by this problem.

For example my POS takes more than 15 minutes to load. Because I have 26.000 products and the compute price method uses a lot browsing through the inherits such like `product.cated_id`, `product.uom_id` and they all takes a huge time to compute.

Same issue in this case.

If I do :
`variant.price` It takes a very long time to get the result.

If I do:
`variant.product_tmpl_id.price` The result is immediate

Could you help me ?


Simple way to reproduce:

1/ Create a new database and install sale module
2/ Launch following script through odoo shell :

```python
# -*- coding: utf-8 -*-
import logging

_logger = logging.getLogger(__name__)
self = self  # noqa

nb_product = 50000

i = 0
while i < nb_product:
    prod = self.env['product.template'].create({'name': 'product_%s' % i})
    i += 1
    if i % 1000 == 0:
        self.env.cr.commit()
        _logger.info("%s Products Created" % i)
```

2/ Launch following script through odoo shell :
```python
# -*- coding: utf-8 -*-
import logging

_logger = logging.getLogger(__name__)
self = self  # noqa


products = self.env['product.product'].search([])

for product in products:
    # Immediate response
    _logger.info('Category Template %s' % product.product_tmpl_id.categ_id)
    # Lagging response
    _logger.info('Category Variant %s' % product.categ_id) 
    break
```
odoo/models.py
"""Return true if the user is member of at least one of the groups in
        ``groups``, and is not a member of any of the groups in ``groups``
        preceded by ``!``. Typically used to resolve ``groups`` attribute in
        view and model definitions.
        :param str groups: comma-separated list of fully-qualified group
            external IDs, e.g., ``base.group_user,base.group_system``,
            optionally preceded by ``!``
        :return: True if the current user is a member of one of the given groups
            not preceded by ``!`` and is not member of any of the groups
            preceded by ``!``
        """
        from odoo.http import request
        user = self.env.user
        has_groups = []
        not_has_groups = []
        for group_ext_id in groups.split(','):
            group_ext_id = group_ext_id.strip()
            if group_ext_id[0] == '!':
                not_has_groups.append(group_ext_id[1:])
            else:
                has_groups.append(group_ext_id)
        for group_ext_id in not_has_groups:
            if group_ext_id == 'base.group_no_one':
                
                if user.has_group(group_ext_id) and request and request.debug:
                    return False
            else:
                if user.has_group(group_ext_id):
                    return False