The migration of the Process List is almost complete now, as you can see from the screenshot.
This will be added to a dialog box in the new Plasma KRunner. KRunner will always be loaded in the background and provides a few lightweight 'programs' that require near-zero start up effort and resources, such as the Run dialog and this new Task List dialog.
The main focus for KSysGuard at the moment has been making it as fast and as lightweight as possible, as well as being easier to use and more user friendly (like the reduction of the number of columns in the default view: no more VmSize (column is hidden by default), VmRSS no longer exists, replaced with much more informative "Memory" and "Shared Memory" display).