[justinmk]

Plugins must opt-in to asynchronous job-control.

There have been drastic changes to the event loop and redraw logic, which makes some operations feel "different" (some slower, some faster). We have not intentionally made any general performance improvements, because the performance bottlenecks of Vim/Neovim hinge on the regex engine (which is primarily maintained by Bram) and vimscript interpretation--nothing else.

Job control is implemented in Neovim for co-process (not in-process) coordination. This means that potentially long-running vimscript calculations can be offloaded to a child nvim process. But Neovim 0.1 does not have a faster vimscript engine per se.