Set keyboard delay/repeat speed in gnome
To change keyboard delay speed in gnome (Ubuntu)
gsettings set org.gnome.desktop.peripherals.keyboard delay 150
gsettings set org.gnome.desktop.peripherals.keyboard repeat-interval 30
# or 11 for wired keyboard
# or 45 (default) for bluetooth keyboard
To get the current setting
gsettings get ...<key>...