This solution fixes long loading screens so why not this.
World of Warcraft_classic_CacheADBenUSDBCache.bin
Log out / Close wow
Find DBCache.bin in the path above
Copy/backup the file to a safe location – just in case
Delete the file in the folder above – Only the file!
Log in to wow – a new file is created by the client
None of your info / settings is deleted – it’s just a junk file that grows bigger and bigger over time. If Blizzard did this automatically many headaches would be gone ;P
It’s worth a shot.