Remove limits without updating summary buffer?

[Niklas Morberg <niklas.morberg@axis.com>]

I keep all messages in my incoming group. I use the agent to
keep a local copy. I expire articles I do not want to see
any more (but they are still available with through the
agent). Expired messages are not shown by default in my
incoming group.

When I want to find an old article I do this:

1. `C-u / w' to show all articles (to remove the limit that
   hides expired messages)
2. `/ s the_subject' or something else to limit the summary
   buffer to messages I am really interested in.

Is there a way to stop gnus from updating the summary buffer
after step 1? It makes the process of finding old messages
slower than it needs to be.

Or should I use another method altogether?

Niklas