I was curious to see what the actual latency was, so I used Pavel Fatin's https://pavelfatin.com/typometer/.
Notes: This system is running Arch, with kernel 7.0.3, scx_bpfland, and i3 on X11. Primary GPU is an integrated Intel GPU.
Using picom:
Terminal Min Max Avg SD
alacritty 20.1 111.4 43.8 18.0
xfce4-terminal 19.1 112.5 49.1 17.9
xterm 12.3 152.6 53.1 26.4
wezterm 28.3 106.0 56.2 15.4
kitty 25.3 115.9 57.2 18.5
ghostty 19.2 611.8 63.4 45.5
konsole 37.9 138.6 68.8 18.5
Using picom --realtime: Terminal Min Max Avg SD
xterm 5.7 63.6 15.2 8.8
alacritty 7.4 48.8 20.2 9.7
xfce4-terminal 8.7 65.3 28.3 12.5
kitty 13.2 64.8 30.8 10.3
konsole 17.3 71.2 31.1 9.5
ghostty 12.9 63.7 33.2 11.6
wezterm 18.0 58.6 33.6 11.1
No picom: Terminal Min Max Avg SD
xterm 4.5 20.4 8.6 1.0
alacritty 9.2 13.3 11.1 0.7
xfce4-terminal 7.4 17.5 11.3 0.9
ghostty 11.2 35.3 18.8 3.8
wezterm 14.1 34.2 22.7 3.7
kitty 12.2 44.3 24.4 5.8
konsole 17.2 30.7 25.0 3.6
Running on the NVIDIA GPU just for fun: wezterm (no picom, NVIDIA) 21.7 51.2 34.8 8.1
wezterm (picom rt, NVIDIA) 22.0 70.9 41.4 11.2
wezterm (NVIDIA) 34.4 146.7 69.0 17.8
Slightly surprised that xterm doesn't top the chart on the picom category.