## Impacted versions:
 8.0 / 9.0 / 10.0
## Steps to reproduce:
* see https://github.com/odoo/odoo/issues/11841
* in a shell
  1. create an in memory record `order = self.env['purcahse.order'].new({....})`
  2. create an in memory record with a reference to the first one `order_line = self.env['purchase.order.line'].new({'order_id': order, ....})`
  3. order_line.order_id is an in memory recordset
  4. create a record for a model that inherits from mail.thread `self.env['product.product'].create({....})`
  5. At this stage order_line.order_id is an empty recordset

## Current behavior:
 In memory records are dropped when a call is done to self.invalidate_cache
## Expected behavior:
In memory records are preserved when a call is done to self.invalidate_cache


There are lot of places where the method `invalidate_cache` is called and the silent removal of the in memory records from all environments has unpredictable effects on fields modified by a computed method or an onchange or even related fields .... Moreover since all caches are invalidated each time you create / write / unlink  (https://github.com/odoo/odoo/blob/10.0/addons/mail/models/mail_followers.py#L111) an instance of a model that inherits from 'mail.thread', the performances of the server are severely penalized.

OPW703903

mod_obj = self.pool.get('ir.model.data')
        act_obj = self.pool.get('ir.actions.act_window')
        result = mod_obj.get_object_reference(cr, uid, 'account', 'action_invoice_tree2')
        id = result and result[1] or False
        result = act_obj.read(cr, uid, [id], context=context)[0]
        inv_ids = []
        for po in self.browse(cr, uid, ids, context=context):
            inv_ids+= [invoice.id for invoice in po.invoice_ids]
        if not inv_ids:
            raise osv.except_osv(_('Error!'), _('Please create Invoices.'))
         
        if len(inv_ids)>1:
            result['domain'] = "[('id','in',["+','.join(map(str, inv_ids))+"])]"
        else:
            res = mod_obj.get_object_reference(cr, uid, 'account', 'invoice_supplier_form')
            result['views'] = [(res and res[1] or False, 'form')]
            result['res_id'] = inv_ids and inv_ids[0] or False
        return result
    def view_invoice(self, cr, uid, ids, context=None):