If the runtime was just added and no code has been executed yet, you’ll find that the runtime shows a gray dot, meaning that it’s stopped. That means once you execute a cell that uses this runtime, the runtime will go through a booting phase (shown by a yellow dot). Because of this booting phase, the first run will take a bit longer than subsequent runs. Once the runtime is running (shown by a green dot), execution should be reasonably fast, depending on what you are trying to accomplish. A red dot and an error message will indicate that there was an error during execution or booting of the runtime.