Text display correct in safe mode.

It could be the work of one of your add-ons, or it could be Hardware Acceleration. How to disable Hardware Acceleration {web link}

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.

Text display correct in safe mode.

Hi Raphaël, one of the other differences between regular and safe/troubleshoot modes is that the shared font list is disabled.

You can test whether that is relevant with this change:

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

(2) In the search box in the page, type or paste gfx.e10s.font-list.shared and pause while the list is filtered

(3) Double-click the preference to switch the value from true to false

I suspect that won't take effect until the next time you quit and restart Firefox.

Sorry jscher2000, it doesn't solved the problem. I will try the other solution, this one from FredMcD. But thank you anyway.

You can try to disable WebRender.

You can look at this pref on the about:config page page to disable WebRender.

• gfx.webrender.force-disabled = true

You can open the about:config page via the location/address bar. You can click the button to "Accept the Risk and Continue".

• https://support.mozilla.org/en-US/kb/about-config-editor-firefox