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List:       kmail-devel
Subject:    Re: for kmail people: a discussion of mail summary files
From:       George Staikos <staikos () 0wned ! org>
Date:       2000-05-16 13:05:47
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On Tue, 16 May 2000, Don Sanders wrote:
> > > Something that takes up a lot of time in KMail when
> > > showing a list of message headers (if not taiking up the most time) is the
> > > cost of operator new. A KMMsgInfo object and a QListViewItem object has to
> > > be constructed for each message header in the list. This means a lot of
> > > calls to operator new which is very slow. I tried to speed this up by
> > > recycling QListViewItems instead of deleting them and creating new ones
> > > this helped a lot but I never really finished this work. 
> > 
> > Do you use KMMsgInfo::init() ?? I just noticed that the QString arguments 
> > misses a "&". E.g. it is "const QString subject" instead of "const QString 
> > &subject". Changing that spares a call to the QString-copy operator.
> > 
> > (They are missing at other places as well I see...)
> 
> I wouldn't think it makes much of a difference since QString is shared
> (reference counted).

   It still calls new at least once though, and at least on AIX, new(ie
malloc()) alone causes kernel contention.  Best to avoid new whenever
possible.  When I was working on Net.Commerce performance I found that the
biggest slowdown on the system was calls to new.  Granted this is a different
type of app, but in a folder of 3000+ messages, it can get heavy.

-- 

George Staikos

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