If you have comps in your project that you don’t expect to work on, prerender them.
https://helpx.adobe.com/after-effects/using/precomposing-nesting-pre-rendering.html#pre_render_a_nested_composition
After Effects will render it to your disk and temporarily replace the comp with the rendered file. This will keep AE from needing to render the comp every time you render and take some time off the final render — it’s much faster to render one video layer than multiple layers with effects. If you find out later you need to make changes, you can switch back to the original comp easily.
To make AE run faster while you’re using it, try this:
– Precomp. It’s much faster to work on a comp with 5 layers than with 100.
– Solo. If you can’t precomp, solo the layers you’re interested in. After Effects will hide and ignore the other layers (and stop calculating their effects) which will speed up previews.
– Turn down preview quality. In the preview panel, set Resolution to Half or Third. Previews will render faster.