https://goo.gl/WcEEG4 The Great Suspender

The Great Suspender

Automatically suspends unused tabs to free up system resources

The Great Suspender is a lightweight chrome extension to help reduce chrome's memory footprint for users that like to have too many tabs open at the same time. This extension will automagically unload each tab while retaining its favicon and title text. A tab can be restored by clicking anywhere on the page when it is needed. This reduces the number of dom elements on the page and ensures no memory leaks or excessive javascripts are running.

16/09/2015: New version 6.21 released.
Bug fixes: Tabs no longer suspend with wrong url. Fixed 'suspend other tabs' button
New features: Dark theme for night crawlers. Improved whitelist with regex support. Suspend actions can now be performed on groups of highlighted tabs.
Please report any issues here: https://github.com/deanoemcke/thegreatsuspender/issues
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Unload, park, suspend tabs to reduce memory footprint of chrome. 
Tabs can auto-suspend after a configurable period of time or be suspended manually. Tabs can be whitelisted to avoid automatic suspension. Suspended tabs are retained after closing and reopening browser, preventing many tabs from all reloading after a restart. Very simple, intuitive interface.

https://goo.gl/WcEEG4