conf.lua

function love.conf(t)
    t.window.fullscreen = true
    t.window.vsync = false
end

main.lua

local lk = love.keyboard
local time = love.timer.getTime()
local ticksPerSecond, tick = 0, 0
local xpos, ypos = 0, 0
local lastdt

love.draw = function()
    local gr = love.graphics
    local y = 0
    gr.print(string.format("FPS %d", love.timer.getFPS()), 0, y)
    y = y + gr.getFont():getHeight()
    gr.print(string.format("dt = %f", lastdt), 0, y)
    y = y + gr.getFont():getHeight()
    gr.print(string.format("updates per second %d", ticksPerSecond), 0, y)
    gr.rectangle("fill", xpos, ypos, 64, 54)
end

love.update = function(dt)
    local now = love.timer.getTime()
    tick = tick + 1
    if now - time >= 1 then
        time = now
        ticksPerSecond = tick
        tick = 0
    end
    lastdt = dt
    if lk.isDown("left") then
        xpos = xpos - 1
    elseif lk.isDown("right") then
        xpos = xpos + 1
    elseif lk.isDown("up") then
        ypos = ypos - 1
    elseif lk.isDown("down") then
        ypos = ypos + 1
    end
end

function love.run()
    if love.load then love.load(love.arg.parseGameArguments(arg), arg) end

    -- We don't want the first frame's dt to include time taken by love.load.
    if love.timer then love.timer.step() end

    local dt = 0
    local time = love.timer.getTime()
    local interval60hz = 60 / 1000

    -- Main loop time.
    return function()
        -- Process events.
        if love.event then
            love.event.pump()
            for name, a,b,c,d,e,f in love.event.poll() do
                if name == "quit" then
                    if not love.quit or not love.quit() then
                        return a or 0
                    end
                end
                love.handlers[name](a,b,c,d,e,f)
            end
        end

        -- Update dt, as we'll be passing it to update
        if love.timer then dt = love.timer.step() end

        -- Call update and draw
        if love.update then love.update(dt) end -- will pass 0 if love.timer is disabled

        if love.graphics and love.graphics.isActive() then
            local now = love.timer.getTime()
            if now - time > interval60hz then
                time = now
                love.graphics.origin()
                love.graphics.clear(love.graphics.getBackgroundColor())

                if love.draw then love.draw() end

                love.graphics.present()
            end
        end

        if love.timer then love.timer.sleep(0.001) end
    end
end