sorry to hear that you're experiencing a performance drop. Unfortunately your graphics card is indeed not really suited for taxing realtime graphics applications, but more of a regular office computer's card. If you're looking for better performance in Enscape I'd very much recommend to go for a gaming graphics card. For instance the Nvidia GTX1060 will already improve performance by several times in comparison to your current graphics card for a moderate amount. There are of course also pricier options that will offer even better rendering performance.
To be able to navigate more smoothly with your current setup I'd recommend to set Enscape's to Rendering Quality at least to "Medium" or "Low" in the Settings window. Reducing the size of the Enscape window will also relieve your graphics card.