The sun is about 92,960,000 miles away from the Earth, and it took Grim about 3 seconds to be shown back on Earth after the camera zoomed back out.

This would make it around 111,552,000,000 miles per hour.

111,552,000,000 is 145388355.918367 times faster than the speed of sound.

Light is 874030 times faster than the speed of sound.

145388355.918367 ÷ 874030 = 166.342523619

This would make Grim around 166 times faster than the speed of light.