Each tab in Google Chrome runs as a separate system process. While this high level of isolation provides great performance and improves security. The downside is that it tends to eat a lottttt of system memory. Not such a great thing when I'm running dev virtual machines on my local machine.
The Chrome team are aware of this and are actively working to improve it. Chrome has an experimental feature that can be enabled called Automatic tab discarding. Instead of keeping all tabs (active and inactive ones) in physical memory, Chrome will move inactive tabs into virtual memory. When the tabs later become active, they will be loaded back into physical memory.