Traffic lights not functioning properly

When approaching southbound the lights only let one or two cars through at a time. I have noticed this seems to be the case whenever there is a car approaching from the eastern side road, as if priority is given to cars approaching those lights. This is causing significant tailbacks along Kingsditch as far back as Hyde lane in rush hour and along Swindon Road as far back as Wymans lane . This is causing an environmental impact due to the sheer volume of cars caught in unnecessary traffic