A reader should be the fastest way to look at a file. Downer opens documents quickly, scrolls smoothly and uses little memory, even when the file is long and full of tables, diagrams and math.
The numbers
All measured on an M3 Max MacBook Pro, against Downer’s own previous version. Each figure is a near-worst case (the 95th percentile) across repeated runs, not the best one.
| What we measured | Downer now | Downer’s previous version |
|---|---|---|
| Reopening a document until the page appears | 15.7 ms | 113 ms |
| Opening and laying out a 2 MB document | 97 ms | 493 ms |
| Finding a word in a 2 MB document | 10 ms | 77 ms |
| Memory with a 2 MB document open | about 80 MB | 204 MB |
Two more from the same Mac:
- 0 dropped frames out of 3,598 in a minute of continuous scrolling
- about 0.03 % of the processor while sitting idle with a document open
Reading an 8 MB document, the largest Downer opens, takes about 35 ms.
What that means day to day
- Double-click a README in Finder and it’s there, without a loading pause.
- Scroll a long document and the text keeps up with your fingers.
- Leave documents open in the background and they sit there using almost none of the processor.
- Find jumps to every match at once, even in a huge file.
Fast doesn’t mean bare
The speed comes with the full reader: GitHub-style Markdown, Mermaid diagrams, math, LaTeX papers, a map of headings, a command palette, 15 themes and an editor beside the preview.