Chrome can release memory from an inactive tab and reload it when you return. That can explain an unexpected refresh, but a website can also expire a session or update itself. Establish which behaviour you are seeing before changing the browser globally.

Save work in the web application and note the page address, time away and result on return. A login screen with a session-expired message is different evidence from an ordinary page reload. Neither behaviour should be treated as a reliable way to preserve an unsaved draft.

Try one deliberate exception

Open Chrome Settings, then Performance. Review Memory Saver and its deactivation level. To protect one essential site from that mechanism, add it under Always keep these sites active. Choosing the currently open site helps avoid a typing error; review the resulting entry so the exception covers the intended service.

Repeat the same harmless task and leave the tab inactive for a comparable period. Return and observe whether the specific reload behaviour changes. Keep a note of the result before adding more sites. Exempting everything removes the benefit you were trying to retain for other tabs.

Recognise what this setting cannot promise

Google lists activities that may already prevent deactivation, including active calls, downloads and partially completed forms. These are not a substitute for saving important work. A browser crash, network failure or the website’s own timeout can still interrupt a task.

If the page still signs you out, check the service’s documented session behaviour or contact its administrator. Remove an exception that does not help. For a computer that remains slow with only a few ordinary tabs, record the wider symptoms before assuming Memory Saver is the whole problem.

Source: Google Chrome Help.