ok! try to remove anything that wont be visible to your rendering. furnitures interior stairs even walls. try to make a second file where you will have only the 3d model no layouts no details nothing just the 3d model. i hope u have more than 2giga of ram . i hope this tips will help you.
Does it help to reduce the refraction setting of the glass perhaps? Check in the material settings dialog > Lightworks Shader tab > Reflectance > Glass > Refraction. Try a value of 1.0 and see if it makes a difference.