Chrome: Keeping tabs open for long periods of time for work is pretty normal. It's why pinned tabs exist. If you only need those tabs a few times a day, though, having them open and taking up memory can be an unnecessary drain. The Great Suspender lightens the load by allowing you to suspend tabs and reload them when you choose.
The extension keeps the tabs open in your browser but removes their content from memory. So, say you want to keep Gmail open while you work, you can suspend it when you're not checking email or want to avoid distractions. It will stay there until you need it, but won't bog your system down. This is also handy if you have to restart your browser. Every tab you suspend is one less tab that will automatically reload at the same time when you restart your browser.