Title: Do not store extra session data
Description: This preference controls when to store extra information about a session including contents of forms, scrollbar positions, cookies, and POST data. Session data could be used for fingerprinting. Meaning of values:
0 = Store extra session data for any site. (Default starting with Firefox 4.)
1 = Store extra session data for unencrypted (non-HTTPS) sites only. (Default before Firefox 4.)
2 = Never store extra session data.
Few secure sites do require session data (=0) to function properly.
Setting recommended: browser.sessionstore.privacy_level = 2
Title: Do not store extra session data Description: This preference controls when to store extra information about a session including contents of forms, scrollbar positions, cookies, and POST data. Session data could be used for fingerprinting. Meaning of values: 0 = Store extra session data for any site. (Default starting with Firefox 4.) 1 = Store extra session data for unencrypted (non-HTTPS) sites only. (Default before Firefox 4.) 2 = Never store extra session data. Few secure sites do require session data (=0) to function properly.
See https://http://kb.mozillazine.org/Browser.sessionstore.privacy_level for more details.