Except operation - Mailing list pgsql-sql

Hi
The query: 
select * from webdata except select * from webdata1;takes abysmally long .How can I optimise it?
The particulars are:

tracedb=> \d webdata
Table    = webdata
+----------------------------------+----------------------------------+-------+
|              Field               |              Type                |
Length|
+----------------------------------+----------------------------------+-------+
| tid                              | int4                             |
4 |
| itemid                           | int4                             |
4 |
| ordering                         | int4                             |
4 |
+----------------------------------+----------------------------------+-------+

tracedb=> \d webdata1
Table    = webdata1
+----------------------------------+----------------------------------+-------+
|              Field               |              Type                |
Length|
+----------------------------------+----------------------------------+-------+
| tid                              | int4                             |
4 |
| itemid                           | int4                             |
4 |
| ordering                         | int4                             |
4 |
+----------------------------------+----------------------------------+-------+
tracedb=> select count(*) from webdata;
count
-----
91155
(1 row)

tracedb=> select count(*) from webdata1;
count
-----9550
(1 row)

Regards
Satya