Learning Lua, implemented the matrix effect for the playdate but there are memory and framerate issues

playdate/source/main.lua

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+local gfx <const> = playdate.graphics
+
+local screenWidth <const> = playdate.display.getWidth()
+local screenHeight <const> = playdate.display.getHeight()
+local glyphWidth <const> = 20
+local numColumns <const> = math.floor(screenWidth / glyphWidth)
+local numRows <const> = math.floor(screenHeight / glyphWidth)
+local numCells <const> = numColumns * numRows
+
+local numGlyphs <const> = 133
+local glyphs = gfx.imagetable.new('images/matrix')
+-- local glyphMap = gfx.tilemap.new()
+-- glyphMap:setImageTable(glyphs)
+-- glyphMap:setSize(numColumns, numRows)
+
+local ditherType = gfx.image.kDitherTypeAtkinson
+local image = gfx.image.new(glyphWidth, glyphWidth, gfx.kColorBlack)
+local numFades <const> = 15
+local fades = gfx.imagetable.new(numFades)
+for i = 1, numFades do
+	fades:setImage(i, image:fadedImage(i / numFades, ditherType))
+end
+-- local fadeMap = gfx.tilemap.new()
+-- fadeMap:setImageTable(fades)
+-- fadeMap:setSize(numColumns, numRows)
+
+local minSpeed <const> = 0.15
+local maxSpeed <const> = 1
+local time = 0
+local speed = maxSpeed
+
+function randomFloat()
+	return math.random(10000) / 10000
+end
+
+local sqrt2 <const> = math.sqrt(2)
+local sqrt5 <const> = math.sqrt(5)
+function wobble(x)
+	return x + 0.3 * math.sin(sqrt2 * x) + 0.2 * math.sin(sqrt5 * x)
+end
+
+local cells = {}
+for x = 1, numColumns do
+	local columnTimeOffset = randomFloat() * 1000
+	local columnSpeedOffset = randomFloat() * 0.5 + 0.5
+	for y = 1, numRows do
+		local cell = {}
+		cell.x = x
+		cell.y = y
+		cell.glyphCycle = randomFloat()
+		cell.columnTimeOffset = columnTimeOffset
+		cell.columnSpeedOffset = columnSpeedOffset
+		cell.glyphIndex = math.random(numGlyphs) + 1
+		cell.fadeIndex = -1
+
+		cells[#cells + 1] = cell
+		-- glyphMap:setTileAtPosition(x, y, cell.glyphIndex)
+	end
+end
+
+playdate.display.setRefreshRate(0)
+playdate.resetElapsedTime()
+
+function playdate.update()
+	local delta
+	if playdate.isCrankDocked() then
+		speed = math.min(maxSpeed, speed + 0.07)
+		delta = playdate.getElapsedTime() * speed
+	else
+		speed = math.max(minSpeed, speed - 0.07)
+		delta = playdate.getElapsedTime() * speed + playdate.getCrankChange() * 2 / 360 -- TODO: tune
+	end
+	playdate.resetElapsedTime()
+	time += delta
+
+	-- local count = 0
+
+	for i = 1, numCells do
+		local mustDraw = false
+		local cell = cells[i]
+		local cellTime = cell.y * -0.03 + cell.columnTimeOffset + time * cell.columnSpeedOffset
+
+		local brightness = math.log((1 - wobble(cellTime) % 1) * 1.25) * 6
+		local fadeIndex = math.max(1, math.min(numFades, math.floor(numFades * (1 - brightness))))
+		if cell.fadeIndex ~= fadeIndex then
+			cell.fadeIndex = fadeIndex
+			mustDraw = true
+		end
+
+		cell.glyphCycle = cell.glyphCycle + delta * 2
+		if cell.glyphCycle > 1 then
+			cell.glyphCycle = cell.glyphCycle % 1
+			local glyphIndex = (cell.glyphIndex + math.random(math.floor(numGlyphs / 2))) % numGlyphs + 1
+			if cell.glyphIndex ~= glyphIndex then
+				cell.glyphIndex = glyphIndex
+				if fadeIndex < numFades then
+					mustDraw = true
+				end
+			end
+		end
+
+		if mustDraw then
+			-- count += 1
+			-- glyphMap:setTileAtPosition(cell.x, cell.y, cell.glyphIndex)
+			-- fadeMap:setTileAtPosition(cell.x, cell.y, cell.fadeIndex)
+
+			glyphs[cell.glyphIndex]:draw((cell.x - 1) * glyphWidth, (cell.y - 1) * glyphWidth)
+			fades[cell.fadeIndex]:draw((cell.x - 1) * glyphWidth, (cell.y - 1) * glyphWidth)
+		end
+	end
+
+	-- print(count / numGlyphs)
+
+	-- gfx.clear()
+	-- glyphMap:draw(0, 0)
+	-- fadeMap:draw(0, 0)
+
+end

playdate/source/pdxinfo

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+name=The Playtrix
+author=Rezmason
+description=A familiar 
+bundleID=net.rezmason.theplaytrix
+version=1.0
+buildNumber=1
+imagePath=path/to/launcher/assets
+launchSoundPath=path/to/launch/sound/file