> only available on the most modern hardware?
Obviously there's something slowing down your Firefox, but it's definitely not to do with how modern your hardware is because 57 is noticeably faster than the previous version on my 2011 MacBook.
There is something slowing it down, but it wasn't under 56. Might be a localised issue, that's always possible.
You can also restore the New Tab behavior you liked pre-Quantum by clicking on the gear in the top right-hand corner.
Actually you can't, you can cut down most things but you can't get previews in preference to icons and you can't get more than two rows (from that menu, you have to go to about:config and browser.newtabpage.activity-stream.topSitesCount [for some reason the browser.newtabpage.rows and ..columns settings are still present but appear to be unused]).
if you turn off the new activity stream you can get the old behavior back.
browser.newtabpage.activity-stream.enabled = false
browser.newtabpage.activity-stream.feeds.section.topstories = false
browser.newtabpage.enhanced = false
browser.newtabpage.enabled = true
seems to respect my 5 columns and 3 rows with large preview icons.
I have all those already; it respects my setting 24 icons (4 rows of 6) rather than giving my prior 3 rows x 5 of page previews.
well I must have some other setting going on because i have 3 rows of 5 and the other setting is at 24 which both can't be true... 15 vs. 24 total.
It takes 12s after launch for my newtab to populate with icons -- which incidentally I dislike compared to the previous page thumbnails -- there's regular stalling when it fails to respond.
I'm prepared to give some space to get acclimated to new versions, there were font problems on lots of pages (including newtab) for me which I've worked through. But I'm failing to see any benefit yet - even then turning the icon super bright has annoyed me ...