使用Canvas录制1080P/30fps屏幕与摄像头画面，30秒后卡顿的问题求助

我写了一段用Canvas合成屏幕流和摄像头流然后录制的代码，前30秒录制都很流畅，但30秒之后视频就开始卡顿了，不管怎么测试都是这个规律，有没有大佬能帮我看看是不是哪里漏了什么细节？

另外说下我的排查情况：我没有用requestAnimationFrame来绘制帧，因为这个API在标签页非激活状态下会失效，不符合我的需求；录制过程中我一直在观察电脑的内存和CPU占用，没看到明显的突增情况，这就更让我摸不着头脑了。

核心代码如下：

const screenVideo = document.createElement("video");
screenVideo.style.display = "none";
screenVideo.srcObject = screenStream;
screenVideo.muted = true;
const webcamVideo = document.createElement("video");
webcamVideo.style.display = "none";
webcamVideo.srcObject = videoStream;
webcamVideo.muted = true;
webcamVideo.onloadedmetadata = () => {
  webcamVideo.play();
};
canvas = document.createElement("canvas");
screenVideo.onloadedmetadata = () => {
  screenVideo.play();
  canvas.width = screenVideo.videoWidth;
  canvas.height = screenVideo.videoHeight;
};
canvasContext = canvas.getContext("2d");

const drawCombinedStream = () => {
  if (!canvasContext || stopDrawingFrames) return;
  canvasContext.clearRect(0, 0, canvas.width, canvas.height);
  canvasContext.drawImage(screenVideo, 0, 0, canvas.width, canvas.height);

  const overlaySize = 250;
  const overlayX = 20;
  const overlayY = canvas.height - overlaySize - 20;
  const overlayRadius = overlaySize / 2;

  const webcamAspectRatio =
    webcamVideo.videoWidth / webcamVideo.videoHeight;

  let drawWidth, drawHeight;
  if (webcamAspectRatio > 1) {
    drawHeight = overlaySize;
    drawWidth = overlaySize * webcamAspectRatio;
  } else {
    drawWidth = overlaySize;
    drawHeight = overlaySize / webcamAspectRatio;
  }

  const offsetX = overlayX - (drawWidth - overlaySize) / 2;
  const offsetY = overlayY - (drawHeight - overlaySize) / 2;

  canvasContext.save();
  canvasContext.beginPath();
  canvasContext.arc(
    overlayX + overlayRadius,
    overlayY + overlayRadius,
    overlayRadius,
    0,
    Math.PI * 2,
  );
  canvasContext.clip();
  canvasContext.drawImage(
    webcamVideo,
    offsetX,
    offsetY,
    drawWidth,
    drawHeight,
  );
  canvasContext.restore();
  setTimeout(drawCombinedStream, 1000 / 30);
};

drawCombinedStream();
combinedVideoStream = canvas.captureStream(30);

备注：内容来源于stack exchange，提问作者tedGuy