Depending on what you sync to your watch will determine how it will perform.... you sync everything, they watch may even take time syncing will your device and even might increase battery usage
On charging it might be a faulty charger maybe, but if your watch still has a warranty you can make use of it, take the watch back to the store, they will resolve it at no cost to your pocket, if it can't be resolved replace it with another....
I'd advice syncing what you would want to use the most remote from the device for better performance not the whole device.... it might result in better performance 🤷♂️
