I always like to think of an unstable particle when I think about time dilation. For example, when it's outside of an atomic nucleus, a neutron will decay in roughly 15 minutes. Let's say you made a device that produces a beam of free neutrons with speed $v$ and measured the time it took for a single neutron in the beam to decay. The decay time you will measure is
$$
\Delta t'=\gamma\Delta t.
$$
$\Delta t'$ is the time for a process to occur in your laboratory - from the neutron's perspective, it's stationary and your lab is moving around the particle. By contrast, $\Delta t$ is the time it takes for the process to occur in the rest frame of the neutron, in this case, 15 minutes. To determine the time you actually measure for the decay of the neutron, you have to compute the Lorentz factor
$$
\gamma=\frac{1}{\sqrt{1-\frac{|v|^2}{c^2}}}
$$
of the neutron. Here $c$ is the speed of light and $\vec{v}$ is the velocity of the neutron. $|v|$ is the speed of the neutron - thanks to the absolute value sign, it's always a positive number.
Now we get to your question. For a neutron travelling 90% the speed of light, $\gamma$ is about 2.29. So in your laboratory, you would measure a neutron lifetime of around 35 minutes. If we instead calculated the speed of a neutron travelling at 99% the speed of light, $\gamma$ is roughly 7.1 and $\Delta t'$ is 107 minutes. The time to decay measured in the frame comoving with the neutron doesn't change but the same process is measured to take a longer time by an observer not moving with the neutron. In that sense, if we wanted to "speed up" time, we should decrease our speed relative to whatever we're interested in, as you guessed.