I think it is a bug in sni-qt that sends too many events to gnome-panel. Other panels like fbpanel do not use indicators so the X11 tray is used there, which does not have the issue.
sni-qt is also unmaintained so I doubt that this will be fixed.
You can use the X11 tray with gnome-panel too, by removing sni-qt package and adding “Notification area” applet to the panel.
If you want to further debug the issue, output of dbus-monitor may be more interesting than strace output.
I think it is a bug in sni-qt that sends too many events to gnome-panel. Other panels like fbpanel do not use indicators so the X11 tray is used there, which does not have the issue.
sni-qt is also unmaintained so I doubt that this will be fixed.
You can use the X11 tray with gnome-panel too, by removing sni-qt package and adding “Notification area” applet to the panel.
If you want to further debug the issue, output of dbus-monitor may be more interesting than strace output.