> My initial attempt was based on placing character images, one-by-one, onto a canvas element, but it was horribly sluggish.
I've done web-based terminal-style renders in a number of different ways for my roguelike [1]. I've done both DOM and canvas renderers. I found that the fastest approach to be:
1. Render each glyph to a canvas.
2. Only re-render glyphs that actually changed.
Doing that was much faster than using the DOM. I imagine I could go even faster using WebGL but at this point, I considered the performance good enough.
For anyone interested, my terminal library is written in Dart and is open source: