To encode more quickly, the media in your sequence should be optimized as much as possible prior to export.
Doing so gives the computer fewer calculations to perform the encode, so its speed improves. Optimizing media allows you to export your sequence free of unexpected problems that might elongate the time of the encoding process. Here are common items to consider when preparing to export more quickly.
Scaling: an optimized sequence contains clips that are the same size as the movie you're exporting.
You can transcode and scale footage to the targeted size in Media Encoder prior to editing, which is what many editors do.
Photos: One should pay attention to not only the scale of video clips but also that of photos and other graphics. These are frequently acquired or created at a frame size that is much too large for use in video post-production, making them less than optimal for faster encoding. These graphics should be optimized to be at the native frame size if they are not to be animated using keyframes. If images are to be animated, a rule of thumb is to crop them to no more than twice the native frame size.
Note: If you import 4K and edit but are exporting a HD sequence, you are scaling, which adds time to an export. If the GPU is enabled for Mercury Playback Engine, scaling is handled on the GPU.
Layered Photoshop files: One should pay attention to many layered Photoshop files and the stress it can put on encoding.
It's best to flatten or optimize these images otherwise prior to encoding (unless you are animating individual layers).
I think TIFF files are a good compromise because they are flattened in an NLE, but in Photoshop, the layers are still accessible for editing, and alpha channels are supported.
Effects: using effects increases the time it takes to encode a movie.
The more effects that are added, the more time it takes to encode. Certain effects both native and third party take longer to encode than others.
Some third party effects (Noise Reduction effects, or example) are well known for significantly increasing export times.
Cutting down any use of unnecessary effects when in the editing phase can save time in the encoding process.
For example, you can transcode footage with Lumetri Color Looks added to them prior to ingesting them into Premiere Pro. This saves time in that the color effect did not need to be processed for encoding, as it was already “baked in.” (see “smart rendering” below).
Preview files: As a strategy, set the codec of your Preview files to the same one as your export codec in Sequence Settings, you can save time in the export process (see “smart rendering” below).
Render and Replace: Use the Render and Replace function for After Effects compositions or any other footage that seems suspect. Use the codec you plan to use in the export process to speed overall encoding. (see “smart rendering” below).
Supported import formats: Use only the supported import formats that are listed in the Help documentation. Odd formats can slow encoding speed.
Frame rate: frame rates in media that do not match sequence settings or export settings will add time to an encode. You can use the Interpret Footage command in the editing process (or by transcoding prior to editing) to conform frame rates.
Variable frame rate footage, such as screen captured media like game play, video from webcams, and video captured by certain mobile phone applications should be converted prior to importing to Premiere Pro and the encoding process. It is supported by Media Encoder and Premiere Pro but you can operate more smoothly with this footage at a constant frame rate.
Unnecessary tracks: remove any unnecessary audio or video tracks or disabled clips from the Timeline. Pay special attention to multi-camera sequences that may have unnecessary and unused tracks, especially audio tracks within nested sequences.
Audio sample rate: ensure that the audio sample rate is the one expected for export. Remove or convert any suspect audio files, especially music that has been acquired from download sites.
Video Previews > Preview File Format: set the preview file so that it matches that of your footage before editing and rendering previews. This can potentially speed up the exporting process at the end of the pipeline.
Rendering previews that are the same file format that you ingest and export comes into play when exporting using the smart rendering workflow.
Exporting with "Use Previews" can greatly speed up the export process if the preview codec matches ingested and exported footage's file format.
Change this in Sequence > Settings.
Note: optimizing media as much as possible in preparing for faster encoding can also assist in avoiding errors in encoding, like "error: compiling movie."
I would add that it is much easier to edit, in general, if the footage is transcoded (optimized) before the editing session begins. JKL keys are snappier and frames immediately appear, as you'd expect.
You can change your ingest settings in Project Settings to import your footage and have it changed to ProRes or Cineform as you are setting up the project. Pretty cool.