I have read through all the answers and nobody that I saw recommended adding RAM.
You are absolutely correct.
If any Windows machine runs more applications and services than will fit into RAM, the machine will start using virtual memory. That means that segments of RAM will be swapped to and from the hard drive.
What this really means is that your computer will slow to a crawl! Moving blocks of memory to something as slow as a spinning hard drive is painfully slow. Even if you have an SSD (solid state drive), it will still have a major impact on system performance.
There are two solutions - running few apps (including closing browser tabs), or install more memory.
Most recent computers will allow up to 16Gb ram, even though they often ship with only 2Gb installed. This is not overly expensive, and addresses the issue in the best way possible.
If the computer is older, it should still allow up to 8Gb ram, which will help. I have an older Toshiba 12.5" laptop with 8Gb installed and an low power dual core i7 CPU. As long as I don't go crazy opening applications and browser tabs, it is still a great performer
Buying a machine with the latest and greatest CPU buys you bragging rights. Buying a machine with a balanced configuration (CPU, RAM, storage, video, buss type) will give you a machine that continues to be useful far past the time you would ever expect.