Version:            (using KDE KDE 3.5.2)
Installed from:    Mandriva RPMs
OS:                Linux

Here is my configuration :
- NFS ( v3 over TCP ) home directory. The NFS server is using hardware RAID ( RAID5 ) and ext3 as filesystem
- many folders with many mail. Test done on a folder with 8275 mails

I noticed that when filtering mail in this folder ( by typing something in the search field ), kmail will use an extremely high CPU usage and the interface will be frozen. After some time, kmail will respond but doing action on the filtered email will be slow. For example right-clicking to select "Answer to" will take a long time to show the contextual menu.

May it be possible that kmail is doing the filtering directly with the files on the disk ? If yes, should kmail use a fast cache for email From-To-Subject-Tags-Status fields and do the fast search with this cache ? It will be faster ( especially for people with config like me ) and will make kmail more responsive. Of course this cache should be in sync whatever a new email is added or removed.
For people saying I should cleaned or organized my folders, i already have many folders and need archive to do search. Each year i will move the email to another folder. So this means that this folders only have mails from 2006.