Inspiron 15 3000 laptop extremely slow

Open Windows Task Manager, click on the performance tab and monitor the graphs while using your computer. If the memory usage is high or maxed at 100%, the computer will operate slowly. If you have 4 gigabytes of RAM, then it's recommend that you at least double it to 8 GB. If you have a traditional hard drive, you may want to consider replacing it with a SSD drive in order to achieve faster loading times and better multitasking. Also, if your hard drive is almost full, that will cause slowdowns as well.