Comment by lhorie

(Disclaimer: I'm the author of Mithril.js)

I looked at this a few years ago and IIRC, it refers to a very specific optimization for recycling DOM nodes in very specific cases. Recycling basically just means reusing pre-existing DOM subtrees instead of naively creating new ones. To my knowledge, Inferno.js and Mithril.js implemented a similar optimization but eventually dropped it because it was difficult to compute when the optimization could be applied and it wasn't worth the complexity (when using virtual dom anyways; my understanding is that imba doesn't do virtual dom)

I recall Imba always had quite nice perf numbers. Recycling DOM nodes did indeed give huge performance increases in synthetic proofs of concepts I did for Mithril.js. A good real world example where it's supposed to shine is tabular data: typically you'd key your rows to get good array diff performance, but this means paginating recreates the entire table from scratch every time. Recycling means reusing the existing DOM instead of re-incurring document.createElement call overheads for the entire table. Of course, in practice it's quite a bit more difficult to deal with edge cases (e.g. DOM state such as element focus)

The two things that I thought were problematic with Imba were a) lack of typing (which has since been addressed) and b) compiled output readability (i.e. it looks nothing like source code). It looks very nice otherwise, and it has come a long way since 7 years ago.