Not sure what the problem is there but I created this similar program and tested it natively and by uploading to itch.io. It reports the expected 60fps in both cases.
Maybe the python server is causing the issue? Note: I also didn't hear any music when running your code.
local t=0 local ts=tstamp() function drawFps() local tmp=tstamp() if tmp==ts+1 then ts=tmp cls(0) print(t,0,0) t=0 end end function TIC() t=t+1 drawFps() end