Start Firefox in Safe Mode {web link} While you are in safe mode;

Type about:preferences#advanced<Enter> in the address bar.

Under Advanced, Select General. Look for and turn off Use Hardware Acceleration.

Poke around safe websites. Are there any problems?

Thank you for your suggestion. I appreciated the clear instructions.

Sadly it made no difference. The lag was still happening after acceleration was turned off.

I don't believe security is the issue because I haven't done much browsing for the last couple of months but I guess it is always possible.

The game is quite old so maybe the last update just made something stop working smoothly.

I've called for more help.

One of the headline changes in Firefox 48-49 is e10s, which separates the browser interface process from the page content process. The performance impact of this can vary a lot between systems, so it would be helpful to know whether you have this feature turned on. To check that, either:

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, check the row for "Multiprocess Windows" and see whether the number on the left side of the fraction is greater than zero. If so, you are using e10s.

If you are using e10s:

To help evaluate whether that feature is causing this problem, you could turn it off as follows:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste autos and pause while the list is filtered

(3) Double-click the browser.tabs.remote.autostart.2 preference to switch the value from true to false

Note: the exact name of the preference may vary, but it will start with browser.tabs.remote.autostart

At your next Firefox startup, it should run in the traditional way. Any difference?

Sorry, could you try something simpler first:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste async and pause while the list is filtered

(3) Double-click the dom.ipc.plugins.asyncdrawing.enabled preference to switch the value from true to false

This might not take effect until the next time you exit Firefox and start it up again.

Here is my error message in the event log....

plugin-container.exe 
  49.0.2.6136 
  5807c043 
  mozglue.dll 
  49.0.2.6136 
  5807b9a7 
  80000003 
  0000e83e 
  317c 
  01d23b641e3e9d7d 
  C:\Program Files (x86)\Mozilla Firefox\plugin-container.exe 
  C:\Program Files (x86)\Mozilla Firefox\mozglue.dll 
  2fcb5aba-09a9-4274-a251-109c5bb0d9d4

Hi AlanWhipple, I'm not sure how this is related to the game lag described by the original poster. Could you start a new question with the full details of your problem and include your Firefox configuration data? Thanks:

https://support.mozilla.org/questions/new/desktop/fix-problems

On that page, scroll down past suggested article to continue submitting your question.