I haven't tried the library, so I can't attest to how fast/slow it is, but I think the point of using web workers is so that the gif can be produced asynchronou

I haven't tried the library, so I can't attest to how fast/slow it is, but I think the point of using web workers is so that the gif can be produced asynchronously, without hanging the whole tab. So if you're producing a really giant image, yes, it would be worth it.