They had some kind of intermediate representation of page renders that was efficiently cached on disk so that it made zero network requests on history navigation. I suspect this same approach also played a part in facilitating the fulltext history search feature I've also never seen in a browser since.

I'm guessing with the way web standards have evolved & become more complex this might actually be impossible to do today while remaining compliant - honestly give me non-compliance though.

I was a die-hard Opera user when it ran Presto - I tried the Chrome version for a while, & I have Vivaldi installed so I can periodically open it & try it out for a while, but absolutely everything since Opera 12, Vivaldi included, has paled in comparison.

Opera 12 was instantaneous in everything it did, even with a session with 100s of tabs open (without auto-unloading them in the background like modern browsers do) & thousands of local emails in M2. The instant history navigation in particular is something no modern browser has even attempted to copy, Vivaldi included (likely because it's a core Chromium functionality that would be difficult to override).

There's just so many tiny details of its UX that were slick & seamless & have been lost. Little things that seem minor but were huge on aggregate like text selection of linkified text - it simply does not work in Gecko or Blink browsers but somehow Presto did it with ease. The page you're leaving remaining fully responsive during navigation to facilitate change-of-mind on mis-clicks, etc. Millions of tiny UX details like this just made the whole daily browsing experience so painless.

> the Guinness head means you're getting less than a pint of actual beer

I hate to be pedantic but pint being volumetric, you're still getting a pint, independent of density. Also - a nitrogen head doesn't dissipate, so you never get a gap.

I'm now curious though whether a nitrogen head is less dense than a CO2 head...

It could well have emerged as a cultural norm from the prevalence of heads, but I've seen it often for very moderate heads, with a gap left above the foam.

> not cheating the customer out of volume

I don't think it's cheating if its the norm. One would expect prices to be set appropriately for the average volume served (i.e. a full glass would be a bonus rather than the gap being a loss).

I do just find it odd, coming myself from the opposite culturally.

I'm from Ireland, where filling beers precisely up to the brim is practically a religion, & many barmen will even take the glass back & top it up if they see the head diminishing too quickly in the space of time it takes you to pick the freshly poured pint up.

One thing that always struck me as odd is how the culture is seemingly the opposite of this in apparent beer meccas like Belgium - not only are the glasses typically much smaller (this is fine) but they also leave massive gaps at the top. The glass capacity is never treated as being close to the rim at all.

You're right that labelling any outage as "Github is down" is an overgeneralisation, & we should focus on bottlenecks that impact teams in a time sensitive matter, but that isn't the case here. Their most stable service (API) has only two 9s (99.69%).

They're not even struggling to get their average to three 9s, they're struggling to get ANY service to that level.

Copilot may be the least stable at one 9, but the services I would consider most critical (Git & Actions) are also at one 9.