Ah, I see.
I retried and now it runs for 21 to 29 seconds for 1 million large
objects with two grants each, 3M total rows inserted.
Yesterday it ran 8 seconds. Unfortunately I do not have the plan from
yesterday saved .
Anyway it looks like just dumping pg_shdepend it is better, and likely
also compresses very well for most users
--
Hannu