Updates, deletes and inserts are very slow. What can I do make them bearable?

I have a very simple update query.

update cu
set screenshot_file_name = tu.screenshot_file_name,
    screenshot_content_type  = tu.screenshot_content_type,
    screenshot_file_size = tu.screenshot_file_size,
    screenshot_status  = tu.screenshot_status

from  cu
inner join tu on tu.cu_id = cu.id

The join has five to six thousand rows in it.

The only indexed field in the update is screenshot_status which is an integer.

I changed the checkpoint settings to

checkpoint_segments = 256
checkpoint_completion_target = 0.9

but it still does not help.

I am having similar problems with deletes and inserts. Trying to
delete even a few thousand records takes forever.  The selects seem to
be just fine.

I am running this on my laptop with no other processes hitting the
database. It's a i5 with lots of RAM and quad core and a IDE drive.

Where is the FAST button for postgres updates? What parameter do I
have to set in order to update 6000 records in under an hour?