Odoo puts in cache all stored fields of a recordset when you access the
first stored field not already in cache. In this particular case, Odoo
will put in cache all stored fields of 'mail.followers', which is
unnecessary and time consuming, especially on models where user follows
plenty of records.
With thousands of followed records, using a read() when searching on
followers is around 2.5 times faster than using mapped().
Record rules based on followers are speed up the same way.
SEINLET Nicolas
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