It’s not possible to do it. That’s how marquee works, it is working flawlessly for a duration you set and then on reset you feel that ‘snap’.
You dont need to loop it 100k times, you can loop it enough so it is good enough enough to work correctly for 30+ seconds, all time above that is in my opinion an extra, noone will sit and watch that effect for a 30+ seconds, and even if they do, it’s not a like website breaking bug?