Why 4K files get so large so fast
A phone or camera shooting 4K at a high bitrate can produce several gigabytes for just a few minutes of footage. Where the file is going, a phone screen, a group chat, a social platform that re-compresses it again anyway, is often a much smaller destination than the resolution and bitrate the camera captured it at.
Hardware encoding, measured
Apple Silicon Macs include a dedicated video encode/decode engine (part of the VideoToolbox framework) built specifically for formats like H.264 and HEVC. QuickCompress uses this hardware path rather than software-only encoding. In the large 4K compression benchmark, a real 1.96 GB native-4K file compressed in 129.6s, down to 515.9 MB. See the full test for the source file, environment, and methodology.
Resolution vs. file size
QuickCompress's "smaller" preset reduces file size while keeping your original resolution and format. If the destination has a hard size ceiling instead, like an email attachment or a chat app's upload limit, target-size mode lets you specify the exact number instead of guessing.
Related
For general questions about the app, see video compressor for Mac. To hit a specific size for sharing, see compress video for email or compress video for Discord.