  The presence of a giant planet in a low-viscosity disc can create a gap edge
in the disc's radial density profile sharp enough to excite the Rossby Wave
Instability. This instability may evolve into dust-trapping vortices that might
explain the "banana-shaped" features in recently observed asymmetric transition
discs with inner cavities. Previous hydrodynamical simulations of
planet-induced vortices have neglected the timescale of hundreds to thousands
of orbits to grow a massive planet to Jupiter-size. In this work, we study the
effect of a giant planet's runaway growth timescale on the lifetime and
characteristics of the resulting vortex. For two different planet masses (1 and
5 Jupiter masses) and two different disc viscosities ($\alpha$=3$\times
10^{-4}$ and 3$\times10^{-5}$), we compare the vortices induced by planets with
several different growth timescales between 10 and 4000 planet orbits. In
general, we find that slowly-growing planets create significantly weaker
vortices with lifetimes and surface densities reduced by more than $50\%$. For
the higher disc viscosity, the longest growth timescales in our study inhibit
vortex formation altogether. Additionally, slowly-growing planets produce
vortices that are up to twice as elongated, with azimuthal extents well above
$180^{\circ}$ in some cases. These unique, elongated vortices likely create a
distinct signature in the dust observations that differentiates them from the
more concentrated vortices that correspond to planets with faster growth
timescales. Lastly, we find that the low viscosities necessary for vortex
formation likely prevent planets from growing quickly enough to trigger the
instability in self-consistent models.
