SCTPS

local c = peripheral.wrap "back".canvas()
local w,h = c.getSize()
local out = c.addText({9, h - 16}, "NO TPS")

while true do
    local game_time_start = os.epoch "utc"
    sleep(1)
    local game_time_end = os.epoch "utc"
    local utc_elapsed_seconds = (game_time_end - game_time_start) / 1000
    _G.tps = 20 / utc_elapsed_seconds
    out.setText(string.format("TPS: %.2f", tps))
    local c
    if tps > 19 then c = 0x00FF00FF
    elseif tps > 15 then c = 0xFFFF00FF
    elseif tps > 10 then c = 0xFF8800FF
    else c = 0xFF0000FF end
    out.setColor(c)

    sleep(1)
end