So I will say that your machine is below our recommended min spec to run the editor, which might be a point of concern when it comes to performance within UE4.
Both documents outline the min spec, and then what we recommend when building a development PC. A lot of people like to build gaming rigs, thinking it will also run the editor well, but the editor requires a much larger amount of RAM due to working with large amounts of uncompressed files and heavy processing when doing things like running lightmass.
I would look into at least increasing your amount of available RAM from 6GB to 16GB or even 32GB if you can afford it. I recently put together a new machine for myself at home, and made sure to have a lot of RAM and a strong processor.
Let me know if you have additional questions.
Cheers,