Since 2015 Google Chrome has had a function for discarding background tabs, those which are not active, in order to use up less RAM memory, and reload them when the user goes back to them. However, until June 2019 this function could be disabled from within the options menu, but the ability to disable this function has now been disabled.
A Chrome extension that stops tab discarding
This extension, Disable automatic tab discarding, can speed up browser functioning and make accessing tab content faster, because the tabs no longer have to be reloaded. However, this does indeed lead to greater RAM memory usage, which could affect the running of your computer and of other processes and make them slower.
If you want to check whether this add-on works properly or not, you simply have to go to chrome://discards in a new tab and you will be able to see how each row has a cross in the column auto discardable.