The compute of `product_variant_count` was highly inefficient
in batch. It is due to `with_prefetch` which remove the prefetch
(reset _prefetch_ids = _ids) of the for loop.
It was added by 05a00fa9d4
which fixed performance issue for the 11.0 about
`sales_count`. But with the new ORM (13.0) compute fields are lazy.
Performance improvements:
For the search_read of the kanban view (Menu: Sale/Products/Products)
with the default pagination (80 items):
Before: 347 SQL request and 0.31 +- 0.2 sec (Python and SQL time)
After: 110 SQL request and 0.14 +- 0.2 sec (Python and SQL time)
task-2439019
Rémy Voet (ryv)
9253643fd0