A serious word of caution here.
1. browser.session.history is simply modifying how many pages of memory can be used to to make your going backward/forward etc. for effective. So in this case modifying this will improve performance or the system (if your resources are short) but it comes at a cost for other aspects of browser behavior that may be less desirable. This is simply a trade off of where the resources are used and how you use the system.
2. pipelining is a method of stacking all the requests from the browser together to prevent waiting for answer each time. this is actually and option built into the HTTP protocol itself. This option might work if the site is using components (all of them) which can support this activity - and the pages can be served this way. However many sites will not want this because it risks impacting the load and performance of their servers and reducing the ability of the infrastructure manage the requests. On some sites this may cause problems or get you kicked off.
3. The initial paint delay is just about loading what ever it gets as soon as it gets it. This is yet another trade off, if there is a lot more content coming then the browser/engine will use even more time and resources painting everything again and you will be actually waiting longer for the “final” page/image. (look up reflow)
4. You do not want to change the ipv6 options unless it there is a clarity on its benefits vs. impact (again may cause problems for some sites).
5. All but the last settings are again only tradeoffs of WHEN actions are done not making them more effective (there is no free lunch. The full path setting is simply a debug setting which rarely improve performance (it means do more processing)
6. The final item actually is the one that can benefit you but again only if that behavior is not a problem for how you use your system. If you have a lot of apps open and switch back and forth, run out of resources then it might be good. Especially if you have limited resources on your system (i.e. 1GB or less of RAM) Again as before this is a left and right hand issue because when you maximize the app it will have to reacquire the resources it needs.
So if your problem is you use FF for hours with lots of tabs and notice a performance impact try the last suggestion (but you have to minimize the app.
A final note. All of these should come with a big disclaimer that you need to remember any of these manual changes because there is no way of understanding their future impact (esp ipv6) and they may not be reset with patches and upgrades.. You don’t want to have problems in the future and never think about those little settings you changed.