You can reduce the amount of time used for rendering in several ways:

Use a lower render quality level.
This approach can be useful at any point in a project
before you do your final output.
Test-render short sections.
Before you apply effects to all parts of a sequence or to
a lengthy part of a clip, apply the effect to a small
section of a clip. Render this selection and check the
results. You can then adjust the settings and apply the
effects to more of your media.
Batch render while you take a break or do other work.
Rendering time isn't actually reduced, but you can make
efficient use of your time by turning your attention to
other things as the computer renders your media.
Use a real-time system.
With a real-time system, many effects and other items
that need to be rendered can be rendered in real time.