adding column with pgadmin gui takes > 800 secs.

I'm having an interesting issue, not sure if it's the server or pgadmin
client:

When trying to add a column (with pgadmin gui) to an already existing
table, a query as shown below is executed on the server:
SELECT format_type(t.oid,NULL) AS typname,
CASE WHEN typelem > 0 THEN typelem ELSE t.oid END as elemoid,
typlen,
typtype,
t.oid,
nspname,
( SELECT COUNT(1)
FROM pg_type t2
WHERE t2.typname = t.typname
) > 1 AS isdup
FROM pg_type t
JOIN pg_namespace nsp ON typnamespace=nsp.oid
WHERE (NOT (typname = 'unknown' AND nspname = 'pg_catalog'))
AND typisdefined AND typtype IN ('b', 'c', 'd')AND typname NOT IN
(SELECT relname FROM pg_class WHERE relnamespace = typnamespace AND
relkind != 'c')
ORDER BY CASE WHEN typtype='d' THEN 0 ELSE 1 END,
(t.typelem>0)::bool, 1

This takes over 800 secs to complete.
Is this normal, against a database with 385 schemas?

(I am posting to this group for the first time, please be kind ;-)