benefits SortFilterProxyModel vs own sort in custom table model?

[anda_skoa]

But i also came over SortFilterProxyModel that I could implement. Is that the better way?

That is a generic way, not necessarily better in ever aspect.

It is "better" in the sense that you don't need to implement anything, i.e. avoiding a source of error/mistake.

Your approach of providing a sorted view on the data is better as it can take the data, its inherent semantic and update behavior into account.

The speed is my most important aspect, as my program is just a search in a database showing results in tableview as you type queries, and it needs to be instant.

I would go with directly presenting the data in the way it should be displayed, i.e. have the model provide the data in the way it should be sorted.
Either by sorting in the model or letting the database already retrieve the values that way.

Cheers,
_