A 5600G is not a bad system at all.
The game should run just fine with an 5600g. I did test everything on a mid/low-range laptop featuring an i5-12500H with its integrated GPU (which is a lot weaker then the 5600g) and it never dropped below 60FPS (Chrome and Firefox).
Probably there is something wrong with your browser settings? Hardware acceleration disabled or something like that?
You could try the official WebGL samples at https://webglsamples.org/ if they do not run at a solid 60 FPS there is something funky going on in your browser.
In case you are using Google Chrome you could check the GPU status by typing:
chrome://gpu
into the topbar. This will open a tab and there should be WebGL and WebGL2 shown as "Hardware accelerated" if it says "Software only" the GPU wont be used and everything will be calculated by the CPU and this is awfully slow.
Please let me know your findings.
Thanks in advance!