My power windows move slower than usual is this my battery?

 I'm trying to figure out if a small annoyance is actually a warning sign that I shouldn't ignore. I have a 2018 Toyota Camry and over the past few weeks, I've noticed that my power windows seem to move up and down slower than they used to. Especially the driver side window – it used to zip up quickly, but now it kind of crawls, especially when the engine isn't running. When the car is running, the windows move a little faster but still not as fast as I remember. My friend told me that slow power windows can be one of the early symptoms of battery issues because the battery provides power for all the electrical components. He said that when a battery starts to fail, the voltage drops, and things like windows, seat motors, and door locks will show problems before the starter motor does because the starter draws so much power that it might still work even with slightly low voltage. Is that true? I haven't noticed any slow cranking or dim headlights yet. The car still starts fine every morning. But I don't want to ignore this if it means my battery is on its way out. Could something else cause slow windows, like a failing window motor or lack of lubrication in the tracks? How can I tell the difference between a battery problem and a window problem? The battery is about two and a half years old, which in Sharjah might be near the end of its life. Should I just replace the battery preventively, or is there a way to test if the battery is the real cause? I have a friend with a multimeter – what should I look for? Also, if the battery is weak, why would the windows be affected but not the starter? That seems backwards to me because I thought starting the engine was the hardest job. Any explanation would help me understand what's going on. I don't want to waste money on a new battery if the real problem is a window motor, but I also don't want to get stranded because I ignored an early warning. Please share your experiences and knowledge so I can make a smart decision.