slow listview item insertion (vista and later)

[nikos]

Under the following conditions, adding a _single_ item to a listview
control
takes ages (10+ seconds!)

* large collection (eg 5000 items in the listview control)
* large icons mode (LVS_ICON)
* windows vista or later

The whole delay occurs when sending the LVM_INSERTITEM message, before
any
painting or sorting takes place

There are no delays for the same listview if set e.g. in report mode,
or in
windows XP

These are the view window styles:

WS_CHILDWINDOW | WS_VISIBLE | WS_CLIPSIBLINGS | WS_CLIPCHILDREN |
LVS_ICON | LVS_SHOWSELALWAYS | LVS_SHAREIMAGELISTS | LVS_AUTOARRANGE |
LVS_EDITLABELS

WS_EX_LEFT | WS_EX_LTRREADING | WS_EX_RIGHTSCROLLBAR |
WS_EX_CLIENTEDGE

LVS_EX_GRIDLINES | LVS_EX_HEADERDRAGDROP | LVS_EX_FULLROWSELECT |
LVS_EX_LABELTIP | LVS_EX_DOUBLEBUFFER | LVS_EX_HEADERINALLVIEWS

I have played with these styles and extended styles but it doesn't
make much difference. The item insertion is fast if I do any of the
following:

* remove LVS_AUTOARRANGE
* remove common control v6 manifest (old painting code)

Using the debug symbols, it looks like the listview is trying very
hard to find an empty slot to put the newly added item:

http://i44.tinypic.com/20aw4mp.png

Any ideas how to speed up without removing LVS_AUTOARRANGE?

thanks
nikos