The problem we were having is with tons of little components scattered around we were setting pretty bad perf problems when loading large data sets. The comp API seems promising in that it shouldn't have the same perf cost as rendering a full component.
I don't think it'll be perfect for all situations but I think it'll be a nice tool to have IF you need it. I don't think most end users will need it often.
I'm all for having more tools at our disposal.
My only concern was that if suddenly all the documentation and tutorials for new users are with the Composition API this might firstly hurt Vue.js adoption and secondly lead to the eventual deprecation of the Options API.
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