I know the BP team are working on perf improvements to the editor, compiler and runtime - will probably be an ongoing process though!
Actually you can re-order custom event params! If you expand the parameter options, there is an up and down arrow you can use!
For organizing wired, did you try a ‘reroute node’? If you drag a wire into space that should be one of the options.
There is a ‘Set Timer Delegate’ node now, that might do what you want for timers. It doesn’t support ‘payloads’ yet though I’m afraid.
Copy/paste in the BP editor does export to text on the windows clipboard (try pasting into notepad!), but there are some things I think are disallowed (e.g. function entry/exit nodes).
Executing BP on another thread is currently only done in one tightly-constrained place (anim blend graph evaluation). We are very wary about allowing that in general because of the ability to read/modify game state while it is being modified elsewhere.
Drag/drop of custom events from the My Blueprint tab makes sense I think, I’ll file a feature request!