Yes particles are typically the kind of things that get better handled by parallelized hardware like GPU so strictly performance-wise, the best approach would probably be to use WebGL.
This is a lot of fun so I played a bit with the code. According to Chromium and Firefox performance analysis, the ratio of spent time just by browser style computing + rendering is almost already 1/3. Then the time spent in VDOM is also quite big since all SVG elements are computed.
So in my opinion, you won’t be able to get a lot of boost anyway. There seems to be a performance issue though when launching the code in Ellie (probably because of debugger), that make it a lot slower than doing it directly without Ellie.
Using Html.Key will not help you on this one. Using Key, will not prevent the VDOM implementation to perform a diff. What is sometimes usefull is Html.Lazy, but in your case it will not help since all points are updated at animation frame. Lazy does not work at the Attribute granularity.
All that being said, I played a lot with the code, and I can share another version I ended up with. The key difference is that I’m keeping a Seed for random generation, so that I can trigger one random generation only when needed for each particle. You can have a look in this Ellie, but I recommend to run without Ellie.