Any program, whether for sale or free, has its own system requirements. Meeting
these requirements is important for a fluid workflow. Common issue nowadays is that the minimum PC specs are starting to get higher and higher. But it's great to know there are 2 things open-source programs tend to have:
1- They aren't that big in file size
2- They aren't that heavy on system resources.
Gimp is exactly that- small and light. It's about a 90mb download and 267mb when installed. It has a light footprint on your system's resources so that even an old pentium can run it, but that isn't to say it won't make use of your system if you have more resources available. It can work on an entry level computer as well as a workstation. It's not like you need a Core i7 for enough calculations or a GTX Titan to power the UI. No. Gimp caters for the tiny setup and the monster setup, the only difference is how far you can go. You may have noticed when you create a new image that the default image size is 640x480. This is a good resolution to support a wide range of PCs but images can get really large at times. You can blame these high resolution images on megapixels, the numbers are jumping so high that even cellphones are competing with cameras!
It's at this point that determines how smooth your experience in Gimp will be. The bigger it gets, the more power you need. In the preferences, Gimp lets you assign how much RAM it's allowed to use and CPU cores so it can handle pushing limits if you need it to. But how far you want to go comes down to the power in your PC.
The CPU, your PC's brain, is responsible for calculating everything that you do. From drawing a simple line with the brush to applying an image effect it's all done by the CPU. How fast these actions get done is controlled by how much power it has. The CPU determines how fast you can do things.
When you create an image that image goes into your RAM, your temporal memory storage. While you're working you are using more and more of it to store things like your image size, undos and redos etc.
RAM determines how much you can do.
Together, these two are responsible for what and how much you can do. If you have this amazing system that does everything imaginable then you've got no worries. But if you have an average PC that doesn't pack power, there are a few tips and tricks you can learn to get a quicker response.