I've been facing with this kind of issue with my Firefox during last 2-3 weeks, maybe more:

Firefox is flickering when typing any initial letter in Google search bar or when typing any initial letter in url link

And I've done Firefox refresh also, uninstalled a reinstalled, having no add-ons, no other themes like default theme, even tried HW acceleration to turn it on/off, nothing's gonna work and the problem has not disappeared. Even the latest update doesn't help at all.

I'm having almost clean Win 10 after buying new desktop (a month ago only) and I won't reinstall the whole system just because of Firefox and its stupid issues. I've been considering myself to switch to Chrome, because of these annoying Firefox issues.

when you use the refresh feature in Firefox then a new profile is created and some personal data (bookmarks and history, form data, tabs) is automatically imported. The current Firefox profile folder will be moved to an "Old Firefox Data" folder on the desktop. Installed extensions and other customizations (toolbars, prefs) that you have made are lost and need to be redone.

It is possible to recover data from the "Old Firefox Data" folder on the desktop, but be cautious not to copy corrupted files to avoid carrying over problems.

Firefox uses two locations for the Firefox profile folder. Location used for the main profile that keeps your personal data (Root Directory on about:preferences).

• C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\Profiles\<profile>\

Location used for the disk cache and other temporary files (Local Directory on about:preferences).

• C:\Users\<user>\AppData\Local\Mozilla\Firefox\Profiles\<profile>\

See also:

• https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles
• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile