So it looks like when clicking a place entry in the launcher, or when clicking the ubuntu button in the panel, the executable for the dash (/usr/bin/unity-2d-places) is started instantly, yet in both cases the actual dash takes ~25 seconds to appear on screen.
However if unity-2d-places is previously started from a terminal, invoking the dash shows it almost immediatly. It looks like the issue is with the D-Bus interface of the dash: the issue can be reproduced by making sure unity-2d-places in not running and invoking the following command:
So it looks like when clicking a place entry in the launcher, or when clicking the ubuntu button in the panel, the executable for the dash (/usr/bin/ unity-2d- places) is started instantly, yet in both cases the actual dash takes ~25 seconds to appear on screen.
However if unity-2d-places is previously started from a terminal, invoking the dash shows it almost immediatly. It looks like the issue is with the D-Bus interface of the dash: the issue can be reproduced by making sure unity-2d-places in not running and invoking the following command:
qdbus com.canonical. Unity2d. Dash /Dash com.canonical. Unity2d. Dash.activateHo me