Hey, how would UE4 run on a 15 inch MBP Retina? 16GB RAM, 2.3 Ghz Intel i7 Haswell, Nvidia Geforce 750M?
Thanks
I have a macbook pro retina 15" Inch with a 16gb ram, 2.6ghz ivy bridge and a GT650m. It runs alright if you set your desktop resolution to 1920x1200. Using it with a multi monitor setup really slows things down. I get an average framerate between 15 to 35 depending on the scene. This is on epic settings. I would not recommend using it for long term development especially as your scenes get complex, but it is workable for sure. However all the interfaces are laggy and it is not a pleasant experience. You can ofcourse lower your settings and get by just fine. The framerate for this scene is around 30, this is on max settings. (No indirect lighting information generated for instanced static meshes? - Rendering - Unreal Engine Forums If you are planning to buy one, then don’t. Get a desktop instead. I use ue4 at work on a desktop and it is a hundred times better and a pleasure to work with.
Here is another thread with similar information Using Ultrabook for UE4 Development - Debugging, Optimization, & Profiling - Unreal Engine Forums
Hi MShahmeer,
Our minimum system requirements are posted in the Frequently Asked Questions section of our main page, UnrealEngine.com.
What are Unreal Engine 4’s system
requirements? You will need a powerful
setup to get started developing with
UE4 right now. Here’s what we
recommend: Desktop PC or Mac Windows
7 64-bit or Mac OS X 10.9.2 or later
Quad-core Intel or AMD processor, 2.5
GHz or faster NVIDIA GeForce 470 GTX
or AMD Radeon 6870 HD series card or
higher 8 GB RAM
These specifications reflect what we feel are the minimum requirements to have a good user experience using the engine.
The engine can run on slower machines in most instances but it is not guaranteed to run or to even provide a good user experience.
The community has put together a forum thread with their machine setups and what their experience is with the engine. The post is titled: [Compatibility List] Unreal 4 - Hardware Feedback]
Take a look there and see if anything matches what you are have or is close. This will give you a better idea than I could about what will best work for you.
I do want to mention as well that the engine is capable of scaling the detail down to give you a better user experience but it will lack features when this is done though. I’m linking the Engine Scalability Settings here to see if this may assist you in what you’re looking for. 
Thank you!
Tim