Make rim braking efficient I have rim brakes on my bike both rear and front, but have been lately decreasing in efficiency, making weird noise when I brake hard and the braking distance has increased too.

Neither my brakes nor my rim have any problems like wear, tension, gap and such. I clean off dust from the rims every now and then. Any ideas what might be contributing to the decreased efficiency of my brakes?
I would look for contamination of the pads and wheels. Oil residue from the roadway may have gotten on to the brake surfaces. Try to clean them with a mild cleaner. I typically use the blue glass cleaner. If the brake pads are several years old they may be getting dried out or glazed. You can try to resurface the rubber face of the pad with a file. The improvement if any tends to be short lived. Avoid sanding the pads with sandpaper as the grit can imbed in the pad and damage the rim. Also consider some performance oriented brake pads. The pad materials have different characteristics such as wet stopping, dry stopping, durability and price.