One thing you can try is to use,

https://support.mozilla.org/en-US/kb/how-do-i-set-sync-my-computer Sync your bookmarks, history, passwords, add-ons and open tabs with another copy of Firefox. Learn how to set up Sync.

https://support.mozilla.org/en-US/kb/how-do-i-choose-what-types-information-sync-firefox We'll show you how to choose which types of information (bookmarks, history, add-ons, and passwords) to share across all your devices through Firefox Sync.

https://support.mozilla.org/en-US/kb/firefox-sync-troubleshooting-and-tips

https://support.mozilla.org/en-US/kb/sync-firefox-bookmarks-and-browsing-history-iOS Sync your passwords, history, tabs and other browsing information across your iOS, Android and desktop computers with Firefox Accounts.

Thanks, so would you say a folder size of 500MB is normal? Once I sync it, where does that 500MB go, cloud, still on one computer? Can I delete it from my computer once it is synced? Appreciate your help!

I do not want to synch over multiple devices a bloated profile, that will slow ALL devices. I am not sure if the Firefox profile is what slowed down my old computer, but I would like to get things in better shape before I synch, if that is what I choose to do. I am happy not synching, but the main thing is trimming down. How can I do that? Thank you.

Only what you choose would be synced. You could start with: You can use sync to share passwords, bookmarks, and history. Then see what you have.

My profile looks like this: . Total Files Listed: . 1135 File(s) 84,734,559 bytes . 278 Dir(s)

You can copy certain files with Firefox closed to the current profile folder to transfer or recover personal data. Note that best is to avoid copying a full profile folder. Note that you should be cautious with copying SQLite database files if you previously had problems.

• bookmarks and history: places.sqlite
• favicons: favicons.sqlite
• bookmark backups: compressed .jsonlz4 JSON backups in the bookmarkbackups folder
• cookies.sqlite for the Cookies
• formhistory.sqlite for saved autocomplete Form Data
• logins.json (encrypted logins;32+) and key4.db (decryption key;58+) for Passwords saved in the Password Manager
  key3.db support ended in 73+; to use key3.db in 58-72, make sure to remove key4.db
• cert9.db (58+) for (intermediate) certificates stored in the Certificate Manager
• persdict.dat for words added to the spell checker dictionary
• permissions.sqlite for Permissions and possibly content-prefs.sqlite for other website specific data (Site Preferences)
• sessionstore.jsonlz4 for open tabs and pinned tabs (see also the sessionstore-backups folder)

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Folder/Directory:
  Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

Sorry, I really have no idea about the Firefox architecture. This profile came from a W7 to W10 computer 5 years ago, and now I got a new W10. So there are 6-10 years of history with this profile. I am just trying to understand what I would need to move to get the bookmarks and auto-fill and that is all I think I want to move.

Are you saying the the sqlite files do not really have any data in regard to Bookmarks and History? If that is the case then I might keep the new Profile that was created when I installed FF on the new computer, and just copy the folders. However it seems like under every storage/default file there is an sqlite file. The storage folders, some have names, but some are just jibberish. I am trying to find where the 253MB of data is in default, but it is hard to find. Most folders are just a few kb.

When I compare the folders in the newly created Profile vs the old, they are very different. Maybe that impacts the computer speed? See images attached

Is the bookmark data spread over multiple files or just "Bookmarkbackups" same with auto-fill data. If you are saying it is in places.sqlite, then what are all the folders for? You can see why this is all confusing to me. I very much appreciate any help. Thank you.

places.sqlite stores bookmarks and history, so copying this file should give you both.

There is no need to copy profile data stored in "AppData\Local", only data in "AppData\Roaming" is important.

Sorry, that was my mistake. I see the old profile was under Roaming. So, what is in all the folders? What is in storage and is it necessary for bookmarks and autofill? If not what does it do? Most of the MB are in the folders, not the files, so I assume they do something. What is favicon? I think I will just copy the Places file and see if that works, leaving all the other files as is in the newly created profile. Thank you.

Also, do I need to copy the places.sqlite-shm and -wal?

What does the webappstore file do? It is pretty big.

Is there a way to combine two places files? Thanks

No, you do not need places.sqlite-shm and -wal and these two files would only be present in a profile if Firefox is running. You should only backup or replace files when Firefox is closed.

webappsstore.sqlite is the legacy file for DOM storage that allows a website to store data locally similar to cookies, but this data isn't sent to the server with each request.

What is in all the folders? What is in storage and is it necessary for bookmarks and autofill? If not what does it do? Most of the MB are in the folders, not the files, so I assume they do something. What is favicon? I think I will just copy the Places file and see if that works, leaving all the other files as is in the newly created profile. Is there a way to combine to places.sqlite files? I just do not understand if I just copy the Places file, what is all the other stuff in the Profile folder for? Thank you.

The favicon is the website icon that you see on the tab in the Tab bar. You also see this icon on a bookmark and history item. If you want to transfer the bookmarks with their favicons then you need favicons.sqlite in addition of places.sqlite.

What is in all the folders? What is in storage and is it necessary for bookmarks and autofill? If not what does it do? Most of the MB are in the folders, not the files, so I assume they do something.

I think I will just copy the Places file and see if that works, leaving all the other files as is in the newly created profile.
Is there a way to combine two places.sqlite files? I just do not understand if I just copy the Places file, what is all the other stuff in the Profile folder for? Thank you.

What is in all the folders? What is in storage and is it necessary for bookmarks and autofill? If not what does it do? Most of the MB are in the folders, not the files, so I assume they do something.

I think I will just copy the Places file and see if that works, leaving all the other files as is in the newly created profile. Is there a way to combine to places.sqlite files? I just do not understand if I just copy the Places file, what is all the other stuff in the Profile folder for? Thank you.