Like I said, I'm using an animation loop, so of course it's going to keep doing things while the user isn't actively interacting. I fully agree there's ways to still improve it, and I might look into switching to entirely event based refreshing, but the 100% cpu core is due to your web browser being unable to offload the svg filters to your gpu. Maybe that's due to your gpu, maybe it's your operating system or web browser that's the problem, I don't know, but that's why people release things as a beta before fully releasing something. Hopefully I can work out most of those kinks, and people giving helpful feedback during beta makes that a lot easier!
For another data point, on my half decent desktop, it uses about 10% cpu and 20% gpu
For another data point, on my half decent desktop, it uses about 10% cpu and 20% gpu