hhmm, skyfire…
….i looked into it, has anyone actually used it on the Epix/Saga ? I ask, because it reads in their FAQ here http://www.skyfire.com/about/beta/ that they do NOT support PDA-phone/WinMobile Pro devices or anything with “unusual screen resolutions”.
And the way they describe their technology/backend, it reads it's like Opera Mini, in which a server-backend pre-packages all your traffic/data to a propietary format/front-end.
And that is where the major difference lies; Opera Mini/Skyfire depend on the server backends 'horse-power' to “pre-format/pre-process” any webcontent for you, so your phone can actually use it.
Opera Mobile/Fennec/PocketIE do all the 'hard work' of HTML/Java/Flash/CSS/XML and what-not processing locally/on the device itself; having only a small fraction of a desktops CPU horsepower available. So, yes, depending how much “multimedia junk” is integrated into a webpage, it can indeed get sluggish. Also keep in mind that Opera Mobile 9.x is currently still in beta stage, so it will still contain debugging-code/-routines to catch issues and verbose internal processes for bugfixing.
After all webpages are a form of programming language that needs to be interpreted in realtime; being able to be platform independent.
On a side note, what about privacy in regards to skyfire ? I mean, nobody sets up a big company, hires a dozen programmers, that want to get paid, for years to make something for 'free'. Usually such “back-end based services” do a very 'nice' job of “consumer profiling for marketing/advertising purposes”. Opera Mobile you've to pay for down the road (usually 25 USD), but at least you wont get profiled/spammed through it 
On the other hand, lets hope the Mozilla Foundation gets Fennec done soon, then we will have a “Firefox for Mobiles”
cheers
@