The general rule is that for an emulator to run full speed, the processor must be 10 times as powerful as the emulated system. Some even say it must be 100 times more powerful...
This is why, despite the NES having a Ricoh 6502 at 1.79mhz it wasn't until we had 100mhz Pentiums that NES emulation was possible.
The NES is extremely simple, has no 3D accelerator, and uses a very very old 8-bit CPU.
Dolphin can emulate the Wii fullspeed on modern systems, and the Wii has a 729mhz Power core processor, and a graphics chip that's basically the same one from the Gamecube (i.e. a 2002 era GPU).
The PS3 has the Cell broadband processor which is essentially a 9 core Power architecture processor at 3.2 Ghz. It also has a Nvidia GPU comparable to an 8800GT. On top of that it has an extremely complex (and protected) OS with a Hypervisor. Emulating these things is many orders of magnitude more difficult than emulating an 8-bit machine from the 80s. Likewise, the 360 has a triple-core Xenon processor and a GPU similar to a ATI X1800.
My prediction, having followed console emulation since 1997, is that you will sooner see a Wii U/3DS emulator than you will see a PS3/360 emulator.
Besides that, if you really want to play PS3 or 360, just buy one. They're cheap. I just recently got a 360 Slim, 250GB and two controllers for $100 on Ebay. I also got a PS3 slim w/ one controller and all hookups for $85, again on Ebay. Try Ebay or Craigslist if you want it locally instead of waiting 20 years for an emulator.
EDIT: Also it should be noted, anything claiming to be an emulator nowadays for modern systems is spyware or ransomware. If you download it and run it, you will most probably get infected and maybe hose your computer or files if you don't have a backup.