Why is it so slow? Tree can't be load in editor for 1 hour, this normal?

As Koderz mentioned you are on the low end of the hardware spectrum. Try to get to a quad core processor, with 16GB of memory, and at least a Nvidia 750GTX as quick as you can. If you need to be the euipment a piece at a time to do the upgrades. Then do the memory upgrade first, followed by the video card, then the processor.

Now one thing you can do, so that you don’t have to load that whole nature pack, because you want only one tree. is to copy over the content you want manually, from one project to another, just maintain the same directory structure, within the content folder, in the target project as existed in the source project. This way you can pick and choose what your going to be spending time on.

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