Is it just with that one site?

Many site issues can be caused by corrupt cookies or cache.

• Clear the Cache and

• Remove Cookies
  Warning ! ! This will log you out of sites you're logged in to.

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

• Cookies; Select Privacy. Under History, select Firefox will Use Custom Settings. Press the button on the right side called Show Cookies. Use the search bar to look for the site. Note; There may be more than one entry. Remove All of them.
• Cache; Select Advanced > Network. Across from Cached Web Content, Press Clear Now.

If there is still a problem, Start Firefox in Safe Mode {web link} A small dialog should appear. Click Start In Safe Mode (not Refresh). 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?

Then restart.

Thank you for the suggestions. Yes, the problem only happens with that site. There are no cookies to delete because I always run the browser set to reject all cookies. The "show cookies" always has nothing to display. So it appears this is not a cookie problem. Clearing the cache is not a workable solution because the problem still happens after the cache has been cleared. Also, the problem happens when hardware acceleration is switched off. I have taken a dump while the browser is in the loop. NOTE: I am using MS IME support for Japanese language on this page and not many folks probably do that.

If you use extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) that can block content then make sure such extensions do not block content. There is security software that can interfere with loading content, so check that as well.

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Thank you for the suggestions. Most of the time the website can be displayed and functions properly. The content in this case only changes depending on what is entered as input for a translation and should be just English text . It seems unlikely to me that extensions would block text content or security products would interfere such content. Also, if a translation does cause the browser to hang, then the same translation will work fine after the browser has been restarted. So the same content gets displayed or loaded correctly. So if the content is being blocked or being interfered with then it is happening inconsistently. It would be nice if there were a tool to determine exactly what Firefox is doing (lines of code being executed) when it goes it to the 65% CPU loop.

I use an add-on for translations, and I bookmarked several translating pages.