It does run well on DOSBox, and was indeed software-only. The only sort of "acceleration" it offered was the option to use VESA BIOS 2.0 video modes.
FWIW I can run it on hardware with my Pentium-90 DOS game box & its Voodoo3 at 800x600x8 (its maximum) with acceptable framerates. It's not quite this fast in DOSBox on my C2D E6300 machine, but that's what lower resolutions are for.
Vertical tabs? How does that work? Seems like Opera is always ahead of the game anyway. Maybe I should be giving that a try. Last time I seriously gave opera a go was around version 4 I think.
How it works? By running the tabs down the side. That gives you room for maybe 30 tabs, and they are always readable and never change position. With widescreen monitors, that's the only thing that makes sense (though it will obviously take a little getting used to).
Firefox extensions like Tree Style Tabs will give you vertical tabs as well.
Stupidity, like virtue, is its own reward.