Yeah it's frustrating. I gave up flashing high beam at the road hogs long ago. Sometimes flashing them will result in unwelcome responses despite how I try to do it in a more polite manner (once and if they didn't notice it after a while, twice). So what to do, ride it out and overtake from the left when there's a safe opening.

err road hogs means well below speed limit. Even if you're at the speed limit. No harm giving way rather than getting rear-ended by an over zealous driver. Not asking you to speed along with the fella.

Also all roads in M'sia got speed limits.