How do I improve the performance of continuously moving BG

Hi, there

My project has 2 continuously moving left backgrounds with different speed, one at 100*dt and the other one at 150*dt, every tick, backgrounds x - it's speed, when the background moving out of screen set it's x to 0. but when I test it, it always have a lag, no smooth moving. then I test C2's autorunner template, it's the same, always have lags, please help. thanks