Performance: pause / resume rendering

At the moment, the renderer will always draw incoming data (manipulate the dom), no matter if the terminal is actually visible to the user. Bigger applications like hyper or vscode, that may render multiple terminals in tabs would benefit a lot (performance and battery drain) if they could suspend the rendering while the terminal element is visually hidden. I think we should offer an API that allows the implementor to pause and resume the renderer.

term.pauseRenderer();
term.resumeRenderer();
term.rendererPaused;

Once the renderer is resumed, it has to immediately redraw to catch up the new state. Any thoughts? I would be tempted to provide a PR 😉

[Tyriar]

My biggest implementation question is how do we store what is the last state that got rendered from the renderer and from where should we start rendering again.

The last state of the renderer will still be in the DOM, all this change would be in its simplest form is some boolean flag which is checked by the renderer and the renderer does nothing. resume would flip the switch back and trigger a full refresh.

[mofux]

I’ll create a proof-of-concept PR with a modified demo that creates multiple terminals that get filled with data continuously and an option to enable / disable the renderer for every single terminal. That way we should be able to inspect if performance is positively impacted.