> I wouldn’t say this polyfill is slow by any measure, but your mileage may vary on mobile devices. My advice would be to use the polyfill only on tablets and desktops at the moment, after you have tested the compatibility and performance extensively on a representative number of devices.
Also, there are js layout libraries used with similar functionality, so one can expect that it is possible to implement this feature with the same efficiency.
Its author, François REMY, is now on the layout team working on Edge. I wouldn't at all be surprised if he was one of the people on the Edge team working on updating their implementation.
There are definitely cases for which the polyfill is likely going to be asymptotically worse than a native implementation, though there will also be plenty of simple cases where the efficiency loss is relatively small.
There is an alpha polyfill effort here. https://github.com/FremyCompany/css-grid-polyfill
Regarding speed, here's the author's take.
> I wouldn’t say this polyfill is slow by any measure, but your mileage may vary on mobile devices. My advice would be to use the polyfill only on tablets and desktops at the moment, after you have tested the compatibility and performance extensively on a representative number of devices.
Also, there are js layout libraries used with similar functionality, so one can expect that it is possible to implement this feature with the same efficiency.