Another data point: it appears that pressing <enter> in a terminal window (tested both gnome-terminal and qterminal) at a zsh shell prompt (but not a bash shell prompt!) results in GNOME Shell being unresponsive for ~4s at 100% CPU and increasing RSS by ~50MB.
Another data point: it appears that pressing <enter> in a terminal window (tested both gnome-terminal and qterminal) at a zsh shell prompt (but not a bash shell prompt!) results in GNOME Shell being unresponsive for ~4s at 100% CPU and increasing RSS by ~50MB.