btop might be measuring the wrong thing here, but alacritty on my box shows 93M using the same interface. I remember benchmarking foot and alacritty (also kitty) pretty extensively a few years ago, and settled on foot.

Though of course, the memory usage on modern machines is really not a major issue, but the configuration update, along with the tmux session death was annoying..

EDIT: Some timing metrics..

  foot -s &
  hyperfine --warmup 8 'alacritty -e true' 'foot -e true' 'footclient -e true'
  Benchmark 1: alacritty -e true
    Time (mean ± σ):      99.0 ms ±  14.2 ms    [User: 58.5 ms, System: 33.4 ms]
    Range (min … max):    82.7 ms … 148.3 ms    32 runs

  Benchmark 2: foot -e true
    Time (mean ± σ):      37.2 ms ±   2.3 ms    [User: 40.3 ms, System: 9.5 ms]
    Range (min … max):    33.8 ms …  43.7 ms    83 runs

  Benchmark 3: footclient -e true
    Time (mean ± σ):      22.8 ms ±   4.3 ms    [User: 0.9 ms, System: 0.8 ms]
    Range (min … max):    18.2 ms …  63.6 ms    133 runs

  Summary
    footclient -e true ran
      1.63 ± 0.32 times faster than foot -e true
      4.35 ± 1.03 times faster than alacritty -e true