Microsoft has a built-in program to defragment hard drives inside Windows.
Free disk space
Usually, most of our programs and data reside in temporary memory (swap) on the hard drive when needed, and will be put into RAM, only a small part is put into memory. The data is fed into the small internal slots with fast access speed and the data on the hard drive is much slower. The system will fill the drive in the mechanism from the inside out, that is, from the exit slots that will push the swap memory memory further away. When the drive is full, the swap memory is also fragmented. This is also one of the reasons why your computer slows down so much. New operating systems have been equipped with features to combat this but unfortunately they only have very small efficiency.
PC infected with malware
When the computer was slow, many people deleted antivirus software on the machine in the hope of improving the speed of the device. But this makes their computers infected with malware. In fact, some users' computers may have installed malware that they did not know. When they remove antivirus software, the computer is no longer protected, the malware will rage and make it slow.
To ensure safety for users, Microsoft integrates Windows Defender quite deeply into Windows 10 system.
Web pages and browsers are becoming more and more complex
Web sites and browsers gradually become more complicated by more advanced web technologies along with the faster average computer speed. This makes their processing capability slower if compared to the system and hardware. To combat this, browser developers have tried to improve software performance but not very effectively. By improving the performance of the software is much harder with hardware.
In short, to fix your slow and slow PC, first check out where it comes from to get the best and most effective processing method. In addition, you should take care of and maintain your PC more often to avoid potential problems.