I'm looking to be able to split columns in metabase as you would on other applications.
This is because of columns containing a number that would be key for creating analytics or joins, but the extra text in the column prevents that use. As far as I can see in the documentation, it's not possible through custom columns but feel it would be a useful function.
But performance will not be as great is if you had a better data model, which didn't require something like this and could make us of indexes too, but shouldn't be a problem on smaller databases.