Rendering with external or internal SSD on MacBookPro

The internal SSD will be faster. Whether you will notice it or not with a Thunderbolt external drive (up to 40 Gbps) is another thing, although those Thunderbolt drives are fairly expensive compared to regular SSDs.

I think using a larger internal drive is the better approach, assuming you can keep enough space free on it for the cache. Not only will it be slightly faster, but for a laptop I think it is preferable to not have to carry around another external device which has to be present for your software to run.

Rendering will be fastest with more RAM; second with the internal SSD; third with an external SSD connected via Thunderbolt 3 or 4; last with an external SSD connected via USB 3.2 Gen 2x2, followed by Gen 2, followed by Gen 1x2. In some cases the GPU & VRAM can also make a difference (depends on application support.)

On Apple Silicon your best choice is more RAM + larger internal SSD; and that implies a new machine.

I don't have your setup (mine is older), but the recommendation has always been to use the internal for rendering. An extenal is fine as a scratch disk, but the rendering process still takes place on the internal since that is where the OS is. However, you should have at least the same space for rendering as you have temp files in your project on your internal and that appears to be a bit small. As well, I'd have 32 GB RAM. T he current laptops are not upgradeable after purchase.

Daniele, unfortunately neither the RAM nor the SSD can be upgraded on a MacBook Pro, since they are soldered to the logic board.

Howard