I don’t think version tables should be deleted 
You might need it for forensics in the future.
If you’re sure it’s causing slow downs then an alternate would be a partitioning table (somewhat risky so do at your own volition)
Or backup and drop previous data. Deleting 2B+ rows isn’t really possible, better option is to copy recent data and drop table like described here: Big DELETEs - MariaDB Knowledge Base