Drop schema & Datapump import extremely slow due to massive amount of LOBs: tunable ?

Hello,

On a bunch of databases (either 12c or 18c) running on ASM, where we

regularly copy data (schema datapump imports), the jobs take hours and hours:

o first we completely drop the schema, it takes 3 hours,

o then do the DP import (takes about the same duration).

Schema is only 380GB big but DBA_SEGMENTS shows 48% of this room

taken by type LOBSEGMENT...

Anybody has an idea whether we could improve the time it takes to

complete both ops: drop schema, and import ?

Addendum: just noticed that 92% (thus 171GB of total) of these LOBs are

concentrated on a single tablespace (these are images)... No magics existing