see extension guru’s list of Firefox tweaks

 

Optimize it

free memory when minimized
Power optimization tips -- the memory-limiter alone makes it worthwhile.

 

1. Limit RAM usage: RAM usage can go up to 1GB+ when you have several tabs open. In the about:config filter, enter browser.cache.disk.capacity or browser.cache.memory.capacity (either of them works). Double click the value that comes up, and enter a value of 5000 for those of you with 512 MB or less memory. Enter a value of 15000 for memory of 512MB to 1 GB.
2. Disable prefetch: Firefox’s annoying feature of prefetching links makes it resource-hogging. Enter network.prefetch-next, and change the value to False.

 

Open search in new tab

1. In firefox, type about:config in the URL box
2. In the filter box, paste this text:

browser.search.openintab

3. Change the value to true by double-clicking the previous “false” text.

 

Stop auto image-resizing

Since 2.0, FF automatically resize large image to fit screen width.

  1. Enter about:config in Firefox address bar.
  2. Enter browser.enable_automatic_image_resizing in Filter field.
  3. change to value to false

 

stop auto page zooming

about:config
browser.zoom.siteSpecific --> false

 

View source in favorite editor

Instructions adapted from MozillaZine knowledge-base

 

  1. enter about:config and filter down to view_source.editor
  2. set view_source.editor.external to true
  3. set view_source.editor.path to something like C:\emacs\emacs\bin\emacsclientw.exe