Why my Hp envy 13-d009nl is running slower and slower?

If you noticed your Hp envy 13-d018TU is running slow, you may need to have a double check. We checked official manual, here is what they suggested: perform regular maintenance to enhance the performance of your computer. Use the tools in this section to optimize your PC, clean up junk files, control when applications run, adjust how your computer uses memory resources, and reduce heat inside your computer.

Also if you are considering replace a hp envy 13-d018TU battery, here is the detail as below:

Price: N$106.44 (Including taxes)

Voltage: 11.4V

Capacity: 3950mAh (45Wh)

Battery cells: 6-cell

Chemical: Li-ion

Battery Color: black

Condition: new original battery

Warranty: 12 months