Not unplayable but considering I'm on a gaming computer it was "less enjoyable" than I wanted it to be. The game itself is very well crafted aesthetically, so once you can find the tradeoffs to get the visuals and rendering working together I think it'll be great.
I didn't have a way to count frames directly, but I'd guess I was living somewhere around 20-40fps on a 4070ti super with 32gb system ram desktop gaming computer. But I was running it in Firefox which can have worse performance than Chromium with regard to displaying a lot of text (I think chrome passes it off to GPU while FF stubbornly renders text on CPU) -- so that could be partially user induced lag by way of using an unpopular browser. Although that may or may not be the case when rendering through Godot.
Edit/update: Gave it a try in Edge, runs pretty playable at default resolution (still choppy full screen). Music is fire though, great work on this.