Bruckner wrote very few organ works for a composer, who has also been a church organist for most of his life.
This Fugue is one of those few pieces.
The tempo is indicated as "Langsame Halbe"
A kind of Alla Breve.
It is a fine fugue; certainly not as spectacular as some of his orchestral compositions.
The Berlin Steinmeyer has very many beautiful 8' and 4' stops.
I played the piece on the 8' and a few 4' stops of the three manuals coupled, which produces a very satisfactory broad but not too loud sound, floating in the big space of the church.
On the last long organpoint of the piece (in the coda) the 32' pedal flue stop is pulled and the speed is somewhat reduced,
The composer suggested FFF in the score, so this is a rather personal choice, based on the stops of this mighty instrument.