Firefox has a nice feature called "Don't load tabs until selected". This setting can be found under the "Tabs" section in Firefox's options window. What it does is prevent tabs from loading in the background until selected by the user. This is useful if you have configured Firefox to automatically load tabs from the last session at startup, or when you load a previously saved browsing session into memory. By not simultaneously retrieving and rendering multiple pages, Firefox's startup time and responsiveness is dramatically improved.

Google Chrome has no such feature but you can add this behavior via an extension called FooTab.

FooTab was inspired by the BarTab extension for Firefox. This was before Firefox natively supported "tabs on demand". BarTab is now irrelevant and hence discontinued, but FooTab continues to serve Google Chrome, until Google chooses to incorporate this behavior.

FooTab has no UI or configuration boxes to speak of. Simply install the extension and forget. When you open a saved session in Google Chrome, the pages won't be loaded automatically. You will see a message instead: "this webpage was blocked by an extension". Shortly afterwards, the page will reload.

FooTab works only for the first 10 seconds after Chrome starts, blocking tabs that are not active from any web requests. After those 10 seconds the web traffic is restored and the extension only monitors the tabs that were previously blocked to reload them when they are activated.

The extension is not hosted in Chrome web store because the developer says he doesn't want to pay the fee that is required to publish an extension to the web store. To install the extension, download the CRX file from this page and save it to the hard disk. Then open Chrome's extension page and drag and drop the CRX file into Chrome's window.

You might have to use another browser to download the CRX file, because Chrome blocks any attempt to download extensions from non-approved websites.