Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options) key, and then starting Firefox. A small dialog should appear. Click Start In Safe Mode (not Refresh).

Is the problem still there?

Hi Fred, Thanks for replying; but I do not understand your reply - I have a reasonable understanding of computers but I have no idea how to start Firefox in Safe Mode, nor what is meant by 'web LInk'.

Would you mind explaining it to me? Thanks, Sandra.

Please read this support article about SafeMode. https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode

I am not too sure exactly what you found, but the results could be fairly normal. If whatever utility it is reports what programs are running on the computer and ranks them in order, of how much power is used then if you are using Firefox actively then maybe it would be high in the list.

This sort of subject would be best discussed elsewhere, however as it is being asked because firefox is getting the blame I will make a short comment.

You probably need to look at tips in other places for saving battery power. For instance turning down the screen brightness may reduce power consumption, and some laptops have power saving options that reduce the speed and power of the computers brain (the CPU). Incidentally you may also wish to look at tips on prolonging the life of the battery, both in terms of its discharge time each cycle, and it lifetime in Years.

• (Power conservation - each cycle) How to Increase Your Windows Laptop’s Battery Life http://www.howtogeek.com/169720/how-to-increase-your-windows-laptops-battery-life/
• (Service Life - long term) Debunking Battery Life Myths for Mobile Phones, Tablets, and Laptops http://www.howtogeek.com/169720/how-to-increase-your-windows-laptops-battery-life/
• A more technical article from 2010 but updated 2016
  How to Prolong Lithium-based Batteries
  Discover what causes Li-ion to age and what the battery user can do to prolong its life.
  http://www.batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

For general Windows 10 related questions and tutorials a popular place to look may be tenforums.com & windowssecrets.com , but there are many other sites on the internet.

P.S. The blue text are links, or hyperlinks or weblinks, whatever term you choose and are clickable and will lead you to the related article or webpage

• https://simple.wikipedia.org/wiki/Link <-- clickable link
  • wikipedia.org/wiki/Link (more complicated)
• If you have not already discovered these they could be of interest
  • Get started with Firefox - An overview of the main features
  • Help & /products/firefox/basic-browsing-firefox
• Browser & more detail

Hi John, yes your posts are helpful and I will look at them; My main problem was that I had NEVER had problems with the battery having to be re-charged after a 'short' time of use UNTIL the Windows10 update last week! Thanks, Sandra

Have you tried Firefox in Safe Mode? Please do.

After that,

Start your Computer in safe mode with networking. Then start Firefox. Try Safe websites. Is the problem still there?

Starting The Computer In Safe Mode;
Free Online Encyclopedia

Possibly the update changed some setting or installed new or changed software. My Windows 10 computer does not have the 1607 Anniversary update of Windows 10 yet.

As the problem is related to the Windows update and many of the factors affecting battery life are Windows settings you probably are better consulting a Windows related site for answers to this problem.

In addition to   John99's   advice may I recommend the Microsoft support forum to post your question:

answers.microsoft.com/en-US/windows/forum/windows_10

Good luck   !

Hi Fred McD.

Yes, I did follow the instructions for starting fire fox in Safe-Mode & so far it looks like it has fixed it.

Thank you to everyone who answered my query, I will look at all the sites suggested, to learn a bit more as well as in case it happens again. Thanks. Sandra.

Safe Mode is a troubleshooting mode that temporarily turns off hardware acceleration, resets some settings, and disables add-ons (extensions and themes). If the problem goes away, that tells us one thing. If it does not, that tells us something else.

It could be the work of one of your add-ons. Type about:addons<enter> in the address bar to open your Add-ons Manager. Hot key; <Control>(Mac=<Command>)<Shift> A)

In the Add-ons Manager, on the left, select Extensions. Disable a few add-ons, then Restart Firefox.

Some added toolbar and anti-virus add-ons are known to cause Firefox issues. Disable All of them.

If the problem continues, disable some more (restarting FF). Continue until the problem is gone. After, you know what group is causing the issue. Re-enable the last group ONE AT A TIME (restarting FF) until the problem returns.

Once you think you found the problem, disable that and re-enable all the others, then restart again. Let us know who the suspect is, detective.