Browser.history expire sites
From MozillaZine Knowledge Base
Mozilla keeps no more than a set number of entries in its browsing history. This helps performance by reducing the amount of information that must be kept in memory while the browser is running. This preference determines the upper cap on the number of websites to keep in history.
Possible values and their effects
A positive integer specifying the maximum number of websites to keep in history. Default value is 40000.
“Edit → Preferences → Browser → History / Browsing History → Remember up to ___ visited pages”
First checked in
Has an effect in