Delete performance

Is there a performance issue deleting rows of a table where one
field is toasted text?

I have a database with two different tables, and delete both based
on timestamp criteria.  One is lightning fast, even for
thousands of rows, the other is very slow.

The first table has a timestamp criteria that is discrete, i.e.,
there are large number of rows with the same timestamp.  This
table has no toasted fields.  This deletes very quickly.

The second table has a timestamp value that is more of a
continuous function (only a few rows will share the same
second of time).  A single field is toasted, and contains
2K to 15K characters.  This deletes very slowly, like only
a couple of records a second.  The table structure is pretty
simple:

  Attribute  |           Type           | Modifier
------------+--------------------------+----------
  name       | text                     | not null
  parse_time | timestamp with time zone | not null
  data       | text                     |

Any hints as to what's going on?  Postgresql 7.1.3,
HP-UX 10.20........


--
P. J. "Josh" Rovero                                 Sonalysts, Inc.
Email: rovero@sonalysts.com    www.sonalysts.com    215 Parkway North
Work: (860)326-3671 or 442-4355                     Waterford CT 06385
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