Where the biggest wins live
Resolution: dropping 4K to 1080p typically cuts the file 50–70% with little impact on phone or laptop viewing.
Bitrate: a 20 Mbps clip re-encoded at 5 Mbps shrinks 75% and still looks great for most content.
Codec: switching from H.264 to H.265 or AV1 saves 30–50% at the same visible quality.
Frame rate and length
Frame rate matters less than bitrate, but a 60 fps screen recording dropped to 30 fps will shrink noticeably with no perceived difference.
Trimming unused intro and outro footage is free file-size savings — never overlook it.
Don't forget the audio
Lossless or 320 kbps audio inside a small clip can dominate the file size. Re-encoding the audio to 128 kbps AAC is invisible to most listeners and shrinks the audio track 60–70%.
A simple workflow
Start with the original master at full quality.
Decide where the video will play (phone, web, TV) and pick a target resolution.
Pick a sensible bitrate (5 Mbps for 1080p H.264 is a good default).
Export with the most efficient codec your audience supports — H.264 for compatibility, H.265 for size.