Holding Shift + ESC can abort long operations like spawning particles. It works differently than simply holding ESC, which itself cannot be used to cancel mid-frame calculations, but is only queried at the end of each frame.
There are dozens of operators whose addition to a flow can result in long calculation times if inserted at the wrong place in the wrong time. I don't think handicapping default values for operators is an ideal resolution to that situation...especially considering that the Spawn operator defaults aren't even the slowdown, it's only when you manually switch to a different emission mode.
There are dozens of operators whose addition to a flow can result in long calculation times if inserted at the wrong place in the wrong time. I don't think handicapping default values for operators is an ideal resolution to that situation...especially considering that the Spawn operator defaults aren't even the slowdown, it's only when you manually switch to a different emission mode.