Check if your Mac needs more RAM in Activity Monitor
The Memory pane displays how much memory your Mac is using, how often it is swapping memory between RAM and your startup disk, and the amount of memory provided for an app and how much of it is compressed memory.
When you have free or unused memory, your computer performance does not necessarily improve. macOS obtains the best performance by efficiently using and managing all of your computer’s memory.
In the Activity Monitor app on your Mac, click Memory.
The Memory Pressure graph lets you know if your computer is using memory efficiently.
Green memory pressure: Your computer is using all of its RAM efficiently.
Yellow memory pressure: Your computer might eventually need more RAM.
Red memory pressure: Your computer needs more RAM.
To learn whether you can add RAM to your Mac, press and hold the Option key, then choose Apple menu > System Information. Under Hardware on the left, click Memory. In the Memory Slots pane, go to Upgradeable Memory to find out whether you can replace or install memory. (If the Memory Slots pane doesn’t appear, upgradeable memory isn’t available for your Mac.)