The LogBook_LID is used as an "ID-Generator" for language depended LogBook tables (e.g. LogBook_EN, LogBook_DE).
Currently an "after delete" trigger of LogBook_LID deletes rows with the same ID in the language depended LogBook_[CountryCode] tables...
Hmmm.. You gave me an idea: If i deactivate (delete) this trigger during this delete transaction and call:
DELETE FROM LogBook_[CountryCode] WHERE TimeStampUtc < strftime('%s',DATETIME('now', '-5 years'))
for each language depended table. This will speed up the whole process.