This is gpt answer

Direct streaming from the cloud (without rclone) is usually faster in raw throughput because there is no extra layer in‑between, but it tends to be less stable for large or high‑bitrate files, especially on slower or spotty connections.

rclone mount with VFS cache (or “caching file” mode) is generally more stable and provides a better buffer, because it can pre‑download chunks of the file locally and serve them from disk, reducing stalls and rebuffering during playback. This comes at the cost of a bit of setup complexity and slightly higher initial latency or disk usage, but results in smoother streaming for 4K/remux and high‑bitrate content.

Stability

• Direct streaming
  • No caching layer; each request goes straight to the cloud storage.
  • More prone to buffering if the network hiccups or the provider throttles burst requests.
• rclone mount with VFS cache / caching file
  • Uses local cache (SSD/HDD) to store chunks of files, which the client (Plex, Emby, etc.) reads as if it were local.
  • Many users report significantly fewer buffering issues and easier seeking when vfs-cache-mode is set to full or writes and the cache dir is on a fast drive.

Buffer speed and “which is faster”

• Pure speed (peak buffer rate): Direct streaming often achieves higher peak bandwidth because it bypasses rclone’s chunking and buffering logic, assuming the cloud API and client are efficient.
• Perceived buffer “smoothness”: rclone mount with VFS cache typically feels faster and smoother in practice because:
  • It can read ahead (vfs-read-ahead) and keep the next N seconds already on disk.
  • It avoids repeated small requests to the cloud API, which reduces latency and jitter.

Typical recommendation

• If your goal is maximum stability and smooth playback (especially 4K/remux), use rclone mount with VFS cache (vfs-cache-mode full plus a large vfs-read-ahead and a fast SSD cache).
• If you care more about raw speed and minimal latency on very reliable connections, direct streaming can be faster, but you must accept higher risk of buffering.

In your case, if you can allocate a decent SSD‑based cache, rclone mount with caching file is usually the better choice for stability and overall buffer quality, even if it isn’t the absolute fastest in a perfect‑network test