The reason for this is actually quite simple.
In previous builds the app just assumed everything was a race and showed the leaderboard is order of position + gaps between players on track.
In the latest build , "qualifying mode" was added, where in non-race sessions, the leaderboard gets ordered by fastest lap + gaps between each drivers fastest lap.
I'll see what I can do to improve performance for this, because I wasn't aware there was such a big performance impact on some people's systems.
When you notice this performance issue could you guys open the Lua Debug app, go to the App:GT7Hud tab and take a screenshot and send it to me?