The following documentation comment has been logged on the website:
Page: https://www.postgresql.org/docs/9.6/datatype-character.html
Description:
Text field is a field that is intended for very big texts.
Performance within Postgres database is commented to be the same as for
normal varchar.
But performance in ETL processes related to such data type is decreased
dramatically, because any process that takes this kind of data needs to
calculate its size on a row level and cannot take bigger chunks of data
based on max size.
So the conclusion would be to use an appropriate character length that
reflects max string size.