Version:            (using KDE KDE 3.4.3)
Installed from:    Gentoo Packages

Sorry for the short rant, but I'm mildly pissed by the poor performance of KMail with more than a few mails. Whatever you do on mail folders with a few thousand emails, e.g. searching, applying filters - cpu consumtion goes up, KMail is crawling and the GUI becomes unusable. Now welcome KCrash:

Using host libthread_db library "/lib/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread 16384 (LWP 22134)]
[KCrash handler]
#5  0x403dd535 in KMMoveCommand::execute (this=0x8832280)
    at kmcommands.cpp:1819
#6  0x403d52d2 in KMCommand::slotPostTransfer (this=0x8832280, 
    result=KMCommand::OK) at kmcommands.cpp:207
#7  0x403d76db in KMCommand::qt_invoke (this=0x8832280, _id=5, _o=0xbfffd230)
    at kmcommands.moc:148
#8  0x403d7a7b in KMMenuCommand::qt_invoke (this=0x36334143, _id=909328707, 
    _o=0x36334143) at kmcommands.moc:2436
#9  0x403db91e in KMMoveCommand::qt_invoke (this=0x8832280, _id=5, 
    _o=0xbfffd230) at kmcommands.moc:2616
#10 0x403dba2b in KMDeleteMsgCommand::qt_invoke (this=0x36334143, 
    _id=909328707, _o=0x36334143) at kmcommands.moc:2691
#11 0x41e05954 in QObject::activate_signal () from /usr/qt/3/lib/libqt-mt.so.3
#12 0x403cc4a5 in KMCommand::messagesTransfered (this=0x8832280, 
    t0=KMCommand::OK) at kmcommands.moc:126
#13 0x403d39fc in KMCommand::transferSelectedMsgs (this=0x8832280)
    at kmcommands.cpp:301
#14 0x403d7265 in KMCommand::slotStart (this=0x8832280) at kmcommands.cpp:199
#15 0x403d76ac in KMCommand::qt_invoke (this=0x8832280, _id=4, _o=0xbfffd490)
    at kmcommands.moc:147
#16 0x403d7a7b in KMMenuCommand::qt_invoke (this=0x36334143, _id=909328707, 
    _o=0x36334143) at kmcommands.moc:2436
#17 0x403db91e in KMMoveCommand::qt_invoke (this=0x8832280, _id=4, 
    _o=0xbfffd490) at kmcommands.moc:2616
#18 0x403dba2b in KMDeleteMsgCommand::qt_invoke (this=0x36334143, 
    _id=909328707, _o=0x36334143) at kmcommands.moc:2691
#19 0x41e05954 in QObject::activate_signal () from /usr/qt/3/lib/libqt-mt.so.3
#20 0x4215768d in QSignal::signal () from /usr/qt/3/lib/libqt-mt.so.3
#21 0x41e1ff23 in QSignal::activate () from /usr/qt/3/lib/libqt-mt.so.3
#22 0x41e278b3 in QSingleShotTimer::event () from /usr/qt/3/lib/libqt-mt.so.3
#23 0x41da2d0f in QApplication::internalNotify ()
   from /usr/qt/3/lib/libqt-mt.so.3
#24 0x41da2eac in QApplication::notify () from /usr/qt/3/lib/libqt-mt.so.3
#25 0x41920345 in KApplication::notify (this=0xbfffeb70, receiver=0x83bdf10, 
    event=0xbfffd920) at kapplication.cpp:549
#26 0x41d964bc in QEventLoop::activateTimers ()
   from /usr/qt/3/lib/libqt-mt.so.3
#27 0x41d4e4f1 in QEventLoop::processEvents () from /usr/qt/3/lib/libqt-mt.so.3
#28 0x41db9410 in QEventLoop::enterLoop () from /usr/qt/3/lib/libqt-mt.so.3
#29 0x41da1eef in QApplication::enter_loop () from /usr/qt/3/lib/libqt-mt.so.3
#30 0x41f1693d in QPopupMenu::exec () from /usr/qt/3/lib/libqt-mt.so.3
#31 0x4027d9ce in KMHeaders::slotRMB (this=0x8322d60) at kmheaders.cpp:2268
#32 0x4027dc8f in KMHeaders::rightButtonPressed (this=0x8322d60, lvi=0x8e0d9e8)
    at kmheaders.cpp:2079
#33 0x40280f80 in KMHeaders::qt_invoke (this=0x8322d60, _id=1109955548, 
    _o=0xbfffdd00) at kmheaders.moc:324
#34 0x41e05954 in QObject::activate_signal () from /usr/qt/3/lib/libqt-mt.so.3
#35 0x4216abe9 in QListView::contextMenuRequested ()
   from /usr/qt/3/lib/libqt-mt.so.3
#36 0x41eed4a2 in QListView::contentsContextMenuEvent ()
   from /usr/qt/3/lib/libqt-mt.so.3
#37 0x41f1f5d5 in QScrollView::viewportContextMenuEvent ()
   from /usr/qt/3/lib/libqt-mt.so.3
#38 0x41f214f7 in QScrollView::eventFilter () from /usr/qt/3/lib/libqt-mt.so.3
#39 0x41eef0c8 in QListView::eventFilter () from /usr/qt/3/lib/libqt-mt.so.3
#40 0x40270d96 in KMHeaders::eventFilter (this=0x8322d60, o=0xbfffdd50, 
    e=0xbfffdd00) at kmheaders.cpp:238
#41 0x41e02e1f in QObject::activate_filters () from /usr/qt/3/lib/libqt-mt.so.3
#42 0x41e02ef2 in QObject::event () from /usr/qt/3/lib/libqt-mt.so.3
#43 0x41e3e65f in QWidget::event () from /usr/qt/3/lib/libqt-mt.so.3
#44 0x41da2d0f in QApplication::internalNotify ()
   from /usr/qt/3/lib/libqt-mt.so.3
#45 0x41da32b9 in QApplication::notify () from /usr/qt/3/lib/libqt-mt.so.3
#46 0x41920345 in KApplication::notify (this=0xbfffeb70, receiver=0x831fe08, 
    event=0xbfffe500) at kapplication.cpp:549
#47 0x41d3b847 in QETWidget::translateMouseEvent ()
   from /usr/qt/3/lib/libqt-mt.so.3
#48 0x41d39d51 in QApplication::x11ProcessEvent ()
   from /usr/qt/3/lib/libqt-mt.so.3
#49 0x41d4db26 in QEventLoop::processEvents () from /usr/qt/3/lib/libqt-mt.so.3
#50 0x41db9410 in QEventLoop::enterLoop () from /usr/qt/3/lib/libqt-mt.so.3
#51 0x41db9366 in QEventLoop::exec () from /usr/qt/3/lib/libqt-mt.so.3
#52 0x41da1ebf in QApplication::exec () from /usr/qt/3/lib/libqt-mt.so.3
#53 0x0804aa7e in main (argc=909328707, argv=0x36334143) at main.cpp:95