xxxxxxxxxx
General advice. The bigger the queryset is
the smaller the batch_size parameter should be.
If you update XXXXX+ rows it will load all the query in the memory,
that will eats up all the RAM and becomes unjustify slow.
`batch_size` From 0 and **max** 1000 is optimal.
`Model.objects.bulk_update(qs_update, fields=[,,,], batch_size=1000)`