• http://howto.helpero.com/howto/Reduce-Firefox-Memory-Usage_4.html - How To Reduce Firefox Memory Usage
• Editing Configuration Files - about:config
• Show Close Tab Button On All Tabs At All Times

  You might want to try this:
  
  Keep Tab Close "X" Buttons Visible:
  
  1. Type about:config in the Firefox address bar. Hit Enter.
  2. Go to "browser.tabs.tabClipWidth" in the list.
  3. Right click, select "Modify", change to desired setting number.
  4. Change setting to 1, default is 140.
  
  Adjust Tab Width:
  
  1. Type about:config in the Firefox address bar. Hit Enter.
  2. Go to "browser.tabs.tabMinWidth" in the list.
  3. Right click, select "Modify", change to desired setting number.
  4. Recommend setting of 0, default is 100.

• Privacy basics - Thunderbird - “Allow remote images in HTML mail” option, re-disable
• Thunderbird portable - importing settings

  Copy the entire CONTENTS of your Thunderbird profile folder (that is the 
  folder named [SERIES OF RANDOM CHARACTERS].default) into the profile 
  folder created by your portable installation on the USB stick, rather 
  than just the Mail folder. 
  Or alternatively, copy the entire Profile folder, not just the contents, 
  and edit the Path statement profiles.ini in the Thunderbird profile 
  folder on the USB stick , or copy the profiles.ini from the Thunderbird 
  folder of the Win 7 PC into the Thunderbird folder on the USB stick. 
  The first method is the easiest because you don't have to mess with the 
  profiles.ini on the USB stick which will already be set to point to the 
  profile folder created by the USB installation, of which you have 
  replaced the contents.  The important thing is to not copy the folder 
  itself, but just the contents. 
  I haven't a clue how you can get your MSOutlook settings on the USB stick. 
  Dave Pyles 

Note: destination folder must be ThunderbirdPortable\Data\profile to be accurate

• ...black screen - Try changing the filter used.

F5-Filter-“Use Windows Media source filter” : Windows Media source filter has better compatibility.