Was curious and tried this out a bit on Linux+X11 on an i7 6700k with the igpu:
stdout [MB/s] idle 50 [ms]
urxvt 34.9 19.8
xterm 2.2 1.9
rxvt 4.3 7.0
aterm 6.0 7.0
konsole 13.1 13.0 note: stops moving when printing large file
terminator 9.1 29.4 note: stops moving when printing large file
st 23.0 11.2
alacritty 45.5 15.5