As I said already in the comments of my addon to you:
You need to start with the biggest SavedVariables.
These increase loading times drastically if > some MB
And it even sums up as each reading and writing of the files is taking time.
The addons itsself do not take that much time for loading screens but you will see them get active after the loading screens end!
e.g. addon1 parsing data from SV of addon/lib2 and transferring it to internal data of addon1 et such.
Logout.
Then check: If you got addons where the live/SavedVariables is bigger than 1mb check what is in there (notepad ++ e.g., check if any old character or account names are in there and delete those tables [tableName = { .... } ] from the SV file:
https://www.esoui.com/forums/showthread.php?t=9235
Before that/After that check those addon's settings ingame if there are ways to strip old data, or rebuild data. Read the addon descripions/FAQ/Docu before that and understand what rebuild means! -> before you loose data make backups of the SV files!
Then remove non used data and even non used SavedVariable files of old addons.
Basically clean those up and check in the addons with the biggest SV files, like LibHistoire, MasterMerchant (GSxxData.lua), CraftStore, InventoryInsight and other addons storing a lot of data of multiple accounts and characters and items at the same time -> if you can lower the timeframe it keeps the data and if that removes old sold info from years ago etc. which you definately do not need anymore.
You can also disable settings ingame in addon settings of e.g. CraftStore to stop tracking all kind of data of all characters, which should decrease the size of the SV a lot as it will not save a lot of itemlinks of recipes or researchable items in the SV then anymore. But if you need that you will have to live with the loading times and I can only recomamdn to disable such addons everytime you do not need them.