There are many things that affect the speed at which a device operates. The most important being processor speed, RAM, and the OS. Finding the most economically suitable threshold for all three of these to begin would be the smart idea. As with any processor, the more powerful it is, the more energy it needs, the hotter it gets, the more energy it needs. You don’t need ‘the best’. Simply look into those phone OS’s that you liked for simplicity over robustness. Multiple applications running at once or in the background cloud any device’s performance. The operating systems that effectively put irrelevant open applications on the backburner, if not closed at all would give the device the snap, thinking about one thing at a time, like concentrating on your math homework and not watching TV. This is probably all common knowledge, and i’m not exactly involved in phone manufacturing, but I do use phones, and i know when they aren’t working at their full potential.

However, when it comes to battery life, if over clocking is done it cannot successfully be done at the cost of an already very limited battery supply.

In my opinion, the newer processors should offer sufficient power without needing to resort to these sacrifices.

Unfortunately, for industrial designers, i don’t think flashy graphics (when they’re programmed well, that is) have anything to do with sluggish performance. Most of the time, they’re just an extra layer on top of a sluggish OS.

That said, i’d really like to see how a phone with a minimalistic but usable interface, and good font rendering preferably, would fare compared to a shiny UI layer in terms of speed…

When it comes to heat sinking the processor, why not use the natural heatsink created by the keyboard holes and surfaces to make it more efficient? While avoiding fingerburns and melted buttons, of course…

maybe have an optional expansion that fits on the back and speeds things up for power users.