Speculative execution in interactive mode
This could increase the percieved speed of the shell by speculatively executing a carefully selected subset of commands before the user presses the return key. But of course I'm aware adding a feature like this is like opening Pandora's box.
The idea comes from Chrome's prerendering feature. Most of their general considerations about resource usage, unintended side effects, etc. should still apply here. I don't think there's prior art in context of system shells out there.
I've been thinking about this feature for a long time. If you think this idea just too crazy, feel free to close the issue.