In general, for comfortable work on outdated devices, competent minimization of program code and the absence of unnecessary background processes play a decisive role. When developers do not overload the web resource with complex banners, the browser consumes much less RAM, which allows the system to work stably. In addition, many modern game providers create special lightweight versions of their slots, where you can manually turn off some visual effects to save battery and traffic. This really helps when there is no possibility to constantly update the equipment. The main thing is to choose sites where the emphasis is on the speed of loading elements, and not on external effects.