How to configure Firefox to automatically reuse the login credentials like IE

You need to enable NTLM Configuration within FireFox. It is very simple to do and should solve your problem:

Open Firefox and type “about:config” in the address bar. (without the quotes of course)
In the ‘Filter’ field type the following “network.automatic-ntlm-auth.trusted-uris”
Double click the name of the preference that we just searched for

Enter the URLs of the sites you wish to pass NTLM auth info to in the form of:

http://intranet.company.com,http://email.company.lan

Notice that you can use a comma separated list in this field.

Move/set Firefox cache location

You can do this by creating a new hidden preference.

Type about:config into the location bar and press enter

Accept the warning message that appears, you will be taken to a list of preferences

Right-click somewhere in the list and select "New > String"

For the name of the preference type browser.cache.disk.parent_directory

For its value type the path to where you want to store the cache, for example d:\fftemp

Next locate the preference browser.cache.disk.enable, it must be set to true, if it is not, double-click on it to change its value

Set the size of the cache to something like 32000 to 512000 by setting browser.cache.disk.capacity (32-512MB)

For more information on this see: https://support.mozilla.org/en-US/questions/768867