Phone age is only part of the picture, really. Two devices released in the same year can behave quite differently because of their memory, processor, battery condition, and software updates. Browser choice matters too, especially when a website uses animations or other features that need more resources. I usually think it makes sense to test a site during normal everyday use rather than judge everything by the first loading screen. If the phone starts getting hot or the battery drains unusually fast, taking a break is sensible. It would be interesting to hear which older models people still use for browser-based games and whether they notice much difference between Wi-Fi and mobile data.
