I'm a bit late to this thread, but as a Haswell Pentium user, low-end Intel 4th gen "Haswell" chips, particularly those that are not Celerons (because those have substantially reduced cache), are probably the best sweet spot between "old" and "good performance".
This is largely because, for reasons still somewhat unknown to this day, Haswell provided a substantial jump in per-clock emulation performance (like 20%-30%) over Ivy Bridge despite only being 5%-10% better per-clock than Ivy Bridge in basically all other workloads.
EDIT: ...Pentium G3258 CPUs, you know, the model with an unlocked multiplier, go for a as low as $15 USD nowadays on ebay (there are in fact currently 3 open listings under $15 USD on ebay, one of which has 2 CPUs available so therefore 4 CPUs available in total for under $15 USD). I know that modern games and Windows OSes really like having more than 2 CPU threads (though our very own wiki caretacker mbc07 is running Windows 10 on a G3258, so what do I know?), but that just feels like a steal to me specifically for Dolphin use - especially if you go the Linux route or specifically make it a more retro-focused PC running Windows 7 or the like.
EDIT 2: And of course, the G3258 also was commonly able to be overclocked even on non-z motherboards... though it apparently doesn't work correctly specifically on Windows 10.
This is largely because, for reasons still somewhat unknown to this day, Haswell provided a substantial jump in per-clock emulation performance (like 20%-30%) over Ivy Bridge despite only being 5%-10% better per-clock than Ivy Bridge in basically all other workloads.
EDIT: ...Pentium G3258 CPUs, you know, the model with an unlocked multiplier, go for a as low as $15 USD nowadays on ebay (there are in fact currently 3 open listings under $15 USD on ebay, one of which has 2 CPUs available so therefore 4 CPUs available in total for under $15 USD). I know that modern games and Windows OSes really like having more than 2 CPU threads (though our very own wiki caretacker mbc07 is running Windows 10 on a G3258, so what do I know?), but that just feels like a steal to me specifically for Dolphin use - especially if you go the Linux route or specifically make it a more retro-focused PC running Windows 7 or the like.
EDIT 2: And of course, the G3258 also was commonly able to be overclocked even on non-z motherboards... though it apparently doesn't work correctly specifically on Windows 10.
Dolphin 5.0 CPU benchmark
CPU: Pentium G3258 @ 4.5GHz 1.24v
GPU: Intel integrated
RAM: 4x4GB Corsair Vengence @ DDR3-1600
OS: Linux Mint of some variety + [VM] Win7 SP1 x64
CPU: Pentium G3258 @ 4.5GHz 1.24v
GPU: Intel integrated
RAM: 4x4GB Corsair Vengence @ DDR3-1600
OS: Linux Mint of some variety + [VM] Win7 SP1 x64
