It truly is an amazing game, and even though it’s past its prime in terms of it being the biggest game in the world, there are still tons of people playing it and I’m having an absolute ball.
(Note, I forgot to say that responsiveness is another hugely important factor in the game’s popularity, of course, but I thought that was kind of the no-brainer that everyone tries to achieve. But come to think of it, it might have something to do with the art design choices as well, because you can have artificially faster animations without it seeming odd, when you have that cartooney style - so again, it all hangs together, it’s all of a piece.)
Also, I laugh at myself for the probable redundancy of this recommendation (I’m sure there’s tons of info in WoW threads here), but as I got mad into addons (now have about 100-odd ) and found them weighing down performance, this forum page from a guy who tested all the big name addons for CPU usage was the most important I’ve found. I’ve switched from the addons I’d been using (most of which are the often community-favoured, “feature rich” ones the author of the post politely mentions as having great functionality) to the ones the author recommends, and found a marked improvement in performance from the accumulation, and actually some of the addons he recommends are even better function-wise than some of the more famous ones I’d been using, having selected them on the basis of venerability, features and up-to-dateness.
Basically, if anyone’s interested the suite of addons at that link is golden, they’re all superbly functional and don’t weigh my computer down (although I suppose it wouldn’t matter if you have a nuclear reactor instead of a toaster like me :) ).
Oh and one last thing - the graphics updates they’ve done are really quite excellent. All the textures are the same, more or less (apart from higher rez versions of the characters), but what they’ve done is add a lot of bells and whistles (shadows, grass physics, etc.) that, again, cumulatively add to quite an improvement from when I remember first trying the game back in 2008 or so.