Resource controls

Resource controls give people the ability to control how much memory their browser uses.

Depending on how you use the browser setting your memory too low may impact browser performance.

Resource controls is for people who want to manually set the memory usage of the browser. Sleeping tabs automatically puts tabs to sleep to free up memory. 

Resource controls is for people who want to manually set the memory usage of the browser. Efficiency mode is designed to maximize battery life by managing CPU usage.

Yes, you can turn resource controls off in the browser settings menu. Go to Settings > System and performance > Resource controls and select the toggle.