They are some of the most common causes for a computer running slow yet they are very important. Most cause temporary slowdown to your system as they continue launching in the background. You can fix this by ensuring that your software is always up to date.
Low disk space
Computers tend to slow down dramatically when they are running low on disk space. Remember that plenty of cache files get generated between your apps and the operating system. When the disk is full such actions take much longer to swap files, thereby affecting the speed at which your computer runs. Always check on the space available and clear out files that are no longer needed from time to time to create more space.
High utilization of the processor
Processes and apps that consume lots of your processor tend to slow other computer operations or tasks. There are so many things that can end up taking up your CPU more than appropriate and they can create an issue. You can quit such apps or processes to free up the CPU and improve operation.
Too many open apps
Another thing that most people overlook yet it can have an effect on the running is opening too many apps at a time. It is a habit that can run you out of RAM or crash the disk resulting in slow speed. Quit all apps that you are not using and work with as few open apps as possible every time.
Not Enough RAM
It is amongst the biggest slowdown culprits. Virtual memory takes over when you are out of RAM and this memory is really slow considering that it relies on the hard disk for information storage. Lacking enough RAM for your needs can also slow speeds. Give up apps you no longer need and re-launch the rest that you are using. If your RAM is not enough for your needs, then it should be time to consider a RAM upgrade.