SUMMARY
A useful feature when looking for a process that I've used in other system monitor apps (ie. the infamous task manager) is that when you press a key (eg. 'S' for steam, 'F' for firefox), the highlighted process cycles through the processes starting with that letter. 
This is useful for when you *sorta* know the name of the process you're expecting. Also, it's much faster than filtering, which takes at least one click to select the searchbox. It also matches similar functionality in Dolphin, which cycles through files of the same initial character when one is pressed with the window focused.

STEPS TO REPRODUCE
1. Open System Monitor
2. Open "Processes" tab
3. Press a letter

OBSERVED RESULT

No action

EXPECTED RESULT

Cycles through processes of the given keypress, in sorted order (ie. highest-lowest memory by default)

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION