Ehm, just how much single-threaded performance do you need for emulators and old games like Warcraft III? What is "the mark", and how do you define it if no current commercially-available CPU gets you there?
Whatever allows me to play those games at 60 FPS without dips. For emulators, no dips from native framerate (in games without big problems). Rogue Leader and Lord of the Rings: The Third Age, both GC titles that I enjoy come to mind; they run acceptably, but there are lots of framerate dips. Wii games are absolutely fine though.
Warcraft 3 probably isn't that fair; the regular games and most custom maps run perfectly, but on the other hand some of them are truly unplayable. Literally single digit framerates after an hour or so. 90% the fault of whoever made them, but still. Even removing all the memory leaking myself didn't help.
Oblivion, when heavily modded really stresses the CPU. 60 FPS is generally only consistent in indoor areas. Morrowind could use help too. But Oblivion in particular drops even unmodded when there are many NPCs on screen and during larger battles. Morrowind, I think, displays drops unmodded as well.
50% more performance would be great (compared to my 4.7GHz 4790K), but I'd reckon double or more is necessary for a "perfect" experience. Not going to happen any time soon, I know.
For a more contemporary example: Just Cause 3. That game without any FPS dips would be incredible, but its CPU demands are through the roof. It's practically unplayable on consoles and on PC, drops are all too common in physics-heavy situations.
CPU bottlenecks are just the most infuriating things ever because there is almost nothing you can do about them. If you have a GPU bottleneck, you upgrade or reduce settings. If you have a CPU bottleneck, you can barely upgrade (I could upgrade to a 4.7GHz Skylake and see a decent improvement, but not enough to spend $600) and settings rarely affect CPU usage.