[Bug 273690] New: walk through windows with alt-tab starts slow with many windows open

[gene smith]

https://bugs.kde.org/show_bug.cgi?id=273690

           Summary: walk through windows with alt-tab starts slow with
                    many windows open
           Product: kde
           Version: unspecified
          Platform: Fedora RPMs
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: NOR
         Component: general
        AssignedTo: unassigned-bugs at kde.org
        ReportedBy: gds at chartertn.net


Version:           unspecified (using KDE 4.6.2) 
OS:                Linux

I often work with many window open on several workspace / desktops. I use no
deskop effects or animations when switching windows. With few window the
alt-tab list comes up fairly rapidly with only a slight but acceptable
hesitation. But with many window (the alt-tab list approaching the screen
height, say) the hesitation or latency after pressing alt-tab before the list
appears approaches a second or more. However, regardless of how many windows
are open or how slow the list appears, once the alt-tab list appears, scrolling
though it is perfectly fast.
I have 4G of memory and don't seem to be using even half of it according to
"system monitor" graphical display. The graphic card is radeon of some sort and
using the free mesa driver which works well with other apps (e.g., smooth
movement with google earth now, unlike with older free radeon drivers) so don't
think this is a problem caused by video performance.

Note: The latency is more noticeable when some other activity for several
minutes occurs between alt-tabs. If alt-tabs are done back-to-back timewise,
the latency is not as apparent. 

Reproducible: Didn't try

Steps to Reproduce:
Open lots of windows on two or more desktop
Work in one window for a few minutes 
Do alt-tab to change to another window 
Time between pressing alt-tab and seeing the list of windows can about 1 sec.

(As noted above, if alt-tab pressed again with little delay since the last time
it was pressed, the latency delay is not as large.)

Actual Results:  
Can take about a seconds for alt-tab window list to appear.

Expected Results:  
Window list should appear "immediately" when alt-tab is pressed regardless of
how many windows are open and how much time has elapsed between alt-tab
presses.


Previous used KDE 3.5.x and it had zero latency when popping up the alt-tab
list regardless of conditions. Kde 4.x has always been sluggish in this regard
compared to 3.5 on several hardware platforms I have used.

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