I've been working on a visualizer as well. It's in python though, so it won't work on websites, and I'm gearing it towards large or fast visualizations. I certainly wouldn't mind sharing feedback and ideas.
Here's a video of it:
On the left is cell-viz, updating 8000 cells with random colors, set to update every 2 milliseconds. It updates faster than the 2 seconds it was set to, but not 2 milliseconds. On the right, my python visualizer is visualizing 10000 'cells' in real time, 20 'cells' changing per frame, but the entire array is still being copied every frame. On top of that, there are also I don't know how many lines in my visualization, which is the main thing slowing it down. (I'm using a test implementation where a line has a 50% chance of being added every frame, and I left it running for several minutes, so there are a lot of lines.)
You might have to trust me on the 'real time' thing, because having a screen recorder, 100 tabs open, cell-viz, and my program running made it hard to record everything in real time.
Hopefully I'll have it ready for use in a few days or weeks. Then we can compare notes!