on delete cascade slowing down delete

I've a large table with a pk and several smaller tables with fk
referencing to it.

deleting from the first table is very slow.

Not all the related fk have indexes but they are VERY small (0 to
100 records) while the main table contain 600-800K records.

the
explain delete p;
doesn't give any clue.

Any hint to track down the problem?

thanks

--
Ivan Sergio Borgonovo
http://www.webthatworks.it