For smooth video editing, your computer needs to be able to process the large amounts of data that are in video files. A high-performance processor is required to is a critical piece of hardware your workstation if you want your video to playback smoothly.
A computer processor is made up of single or multiple cores which receive instructions and then performs calculations or actions based on those instructions. For video editing, more cores means that you have more processing power which translates into faster video performance.
So how many cores do you need? That depends on the type of editing you are doing and what software you are using. Each editing software has minimum requirements for optimal performance. Here are a few of the most used softwares and their requirements.
The type of editing you are doing also plays a big factor into your system requirements. If you are just doing simple cuts, your computer can have less processing power, but if you are doing motion graphics and effects you'll need more processing power so more cores and a dedicated GPU will be needed to ensure smooth playback and editing.
No matter what editing you are doing, a quad core is the minimum recommended number of cores you need in your computer. If you are performing more complex video editing, 6-10 cores are recommended.