is there a list of games in dolphin that is very demanding
Dolphin does not actually need a high end cpu. Just a decent CPU. My previous i5-4430 was more than enough to run everything at full speed when using the latest development builds (or at least Dolphin 5.0). And that CPU was just decent.
Star Wars Rogue Squadron 2 and 3. Both are insanely hard on the CPU especially at higher EFB resolutions.
Any game that needs MMU to work will need beefy CPUs, basically...