More RAM won't speed up Plex transcoding.

It will just reduce swapping. Transcoding is a CPU/GPU job, not a memory bottleneck. If your server is swapping hard (check htop or free -h), 16GB will make it feel snappier for everything else. But Plex’s actual transcoding speed won’t change.

At 8GB, you’re usually fine for a few concurrent streams and a handful of lightweight services. The problem shows up when you have lots of users, database caches, or container overhead. If you’re not seeing swap usage, you’re fine. If you are, 16GB is cheap insurance.

Don’t expect a magic performance jump. Just less stuttering when the system runs out of memory.

If you have the slot, spend the $30. Future you will appreciate not having to close tabs to play a movie.