Version 72 (modified by trac, 9 years ago) (diff)


Hacking Firefox for Maximum Performance with Tor


Tor is known for being secure but slow. If you want to improve browsing speed a bit, please follow the following simple instructions for tweaking the Firefox web browser's settings:

Procedure 1

First, open Firefox's advanced settings menu by running about:config from the address bar. Upon entering this address, you will see a long list of internal settings. Modify the following ones and set them to the suggested values shown here for maximum performance:

{{{ network.http.keep-alive.timeout:600 (300ms default is OK usually, but 600 is better.) network.http.max-persistent-connections-per-proxy:16 (Default is 4) network.http.pipelining:true (Default- false. Some old HTTP/1.0 servers can't handle it.) network.http.pipelining.maxrequests:8 (No default) network.http.proxy.keep-alive:true (Default- true, but double check) network.http.proxy.pipelining:true (Default- false) }}}

Afterwards, just restart the browser and experience the difference! For some automated additional performance hacks, check out FireTune. Currently, FireTune is only for Win32, but you can do the same tweaks manually with the help of this page. Additionally, there is the FasterFox extension that is easy to install, and is also platform independent!

Procedure 2 - an update and addendum to Procedure 1

These results were arrived at empirically, using the win32 bundle, Tor & Privoxy & Vidalia bundle:

You will need the following tools...

Tor Button - enable / disable TOR access in FireFox

This provides an optional button or text in the bottom right of the browser window in Firefox. This allows you to switch Tor on and off.

FasterFox - Modify performance related settings in FireFox

This plugin modifies the networking and cache settings for Firefox. The following settings need to be modified.

  • Initially you need to select 'Custom' in the FasterFox Options. This allows you to use your own detailed options, rather than the default schemes supplied.
  • Select the Cache tab.
    • Enter a Memory Cache Capacity of >= 8mb
    • Enter a Disk Cache Capacity of >= 8mb
  • Select the Connection tab
    • Enter Max Connection >= 128
    • Enter Max Connection Per Server >= 10
    • Enter Max Persistent Connection Per Server >= 8
    • Enter Max Persistent Connection Per Proxy >= 8
  • Select the Pipelining tab
    • Ensure all 3 tick options are enabled
    • Enter Max pipelining requests >= 10

Prio - Increase Tor process Priority (win32)

You will also realise a substantial increase in performance by increasing the process priority for the Tor process. You can do this in Task Manager after you identify tor.exe. If you want to persist the process priority you will need a Task Manager addon. An effective tool for doing this is Prio. This tool can only be used in a non-commercial setting, unless you license it. I dont recommend modifying the process above 'high'. If Tor crashes or freezes windows will become unresponsive. Setting it to 'Above Normal' is a good start.

TCP/IP - Optimise 2K/XP's throughput (win32)

Windows XP has a self-tuning IP stack, but it can still benefit from a little help. Using the TCP Optimiser tool from above you can tune the RWIN, SACK OPTS (rfc 2038), and tcp1323opts controlling window scaling. The tool has one button optimise. This setting is sufficient to benefit from immediate increases to Tor throughput. To increase throughput further you can try experimenting with lower values of the IP TTL (Time To Live). Values as low as 32 will work and result in improved performance. Also experiment with RWIN's > 1040000, which is the setting that 'Optimal' in the tool gives you. Doubling this is a good start.

Remove the limit on TCP connection attempts XP SP2 (win32)

Remove the limit on TCP connection attempts has an interesting article detailing this restriction introduced in XP SP2. Microsoft have restricted the amount of half-open TCP/IP connections with the proviso that it would reduce the pace that worms spread. As noted by SpeedGuide, internet worms spread isotropically (multi-directionally) and so their infecton rate is exponential. As such, placing a constant (limit) on the rate of connection creation for every computer running XP SP2 will slow the rate of worms spreading (for that group of computers) but not by much. Consider the population of humans on the planet. Its over ~6 billion.

Supposing all these people are running Windows XP SP2, with rate limited half-open connections. To infect the entire population of computers would take: We are assuming optimum forward infection here. In the first second we have infected 10 machines. The 2nd second to elapse will cause (10 x 10) + 10 = 110 computers to be infected. The 3rd second to elapse would cause:

( (10 * 10) * 10 ) + (10 * 10) = 1100 computers to be infected. So the number of computers infected for every second that elapses is : computers infected = ~ 10 elapsedSeconds

In 12 seconds, we would have 10 12 = 1 billion computers infected. Full infection occurs before 13 seconds have elapsed !

This is all skewed by network topologies and routing algorithms, but they would affect a non-limited network in an identical manner. So the affect is a theoretical minimum of 12 seconds of additional notice to act against the worm. To all intents and purposes, this is useless.

Of much more interest is the effect on ANY network that relies on many open connections, such as Tor and a host of P2P applications. The effect here is a slow down of communications, with the limit acting as the catalyst.

Use the Event ID 4226 Patcher to mitigate against this.

DNS - reducing latency

For faster DNS performance generally and with TOR(on win32 only i'm afraid) see...

Also for all OS'es see...

The proof is in the pudding

With the changes made from Procedure 2, you can realise a sustained throughput of >100k, peaking at ~200k or more. These figures are based on the highest TOR bandwidth settings (>1.5mbps), through a 2mb connection. You will also experience much lower DNS latency in general. TOR at version 0.1.2.x uses an Asynchronous DNS resolver, the DNS tips above positively affect TOR traffic.