The reason for the lag is a hardware issue between the two graphics cards. Draw calls can influence your CPU/GPU in more ways than just the draw calls. For instance, if you had 400 trees in your scene and they were all 250 triangles, this would be less intense on your computer than 400 trees that are 1000 triangles. These of course being individual mesh’s that are their own draw call as opposed to foliage.You said the geometry isn’t intensive. Not intensive as in 500 tris and below or 25,000 and below?
If you are using HLOD’s there is a known issue with the LOD’s popping in all at once. So say you have a bunch of foliage. And then you add the HLOD system to handle the different clusters. Instead of a gradual LOD transition of your LOD’s, based on culling, a number of LOD’s all pop in at once when changing your FOV. This could be causing the issue where you walk every five feet and then your LOD’s transition. This causing those draw calls to be called with the rest of your calculations when running UE4.
Yes, the GTX 580/590 is reasonably adequate. It will run modern games ok. However, the difference between developing a game and running a game is one is packaged. All of the development is over. Everything has been optimized to run within certain specs that is specified by the company to run their product. All of the functions, tools, calculations, that are associated with the development software are not present and the functionality of the game is all that is running on your machine.
The fact that you are able to work fine on a higher end machine is indicative that there is an issue from one machine to the next. You said “heaven forbid i attempt to use that in unreal engine 4,” enforces this theory further. If you have a machine that is able to develop I would recommend using that machine for your development.
This directly correlates to the issue you previously posted : Profilegpu not accurate? - World Creation - Epic Developer Community Forums
Andrew Hurley has already given multiple links to our documentation regarding optimization and how to profile your GPU within your project. I can open the Blueprints map from learning and it doesn’t dip below 80 or 90 fps on this setup.
OS Windows 7 Professional
Intel(R) Xeon(R) CPU ES-2620 0 @ 2.00 GHz 2.00GHz
32GB Ram
GeForce GTX 770
Version 347.09
Since you have already posted on this issue before, and I have looked through the thread, without a project I cannot begin to test whether the issue is project or card based. Based on all of this information I believe the issue lies either within your card or possibly your project.