  Single-field models of inflation might lead to amplified scalar fluctuations
on small scales due, for example, to a transient ultra-slow-roll phase. It was
argued by Kristiano $\&$ Yokoyama in arXiv:2211.03395 that the enhanced
amplitude of the scalar power spectrum on small scales has the potential to
induce a sizeable 1-loop correction to the spectrum at large scales. In this
work, we repeat the calculation for the 1-loop correction presented in
arXiv:2211.03395. We closely follow their assumptions but evaluate the loop
numerically. This allows us to consider both instantaneous and smooth
transitions between the slow-roll and ultra-slow-roll phases. In particular, we
generate models featuring realistic, smooth evolution from an analytic
inflationary potential. We find that, upon fixing the amplitude of the peak in
the power spectrum at short scales, the resulting 1-loop correction is not
significantly reduced by considering a smooth evolution. In particular, for a
power spectrum with a tree-level peak amplitude potentially relevant for
small-scale phenomenology, e.g. primordial black hole production, the 1-loop
correction on large scales is a few percent of the tree-level power spectrum.
