Not a whole lot. The Shuttle's max acceleration during launch was around 3 gees, and at this phase I believe it was more like 2.5 gees. 0.161 seconds at 3 gees is under 5 meters/second change in speed.

Thanks very much. I had always assumed the Shuttle's max acceleration was a lot higher than that, given how fast the thing seems to get moving in such a short amount of time.

It takes about eight minutes to get to orbit. Which is quick, but not super quick. Reasonable accelerations reach really high speeds when you just keep doing them for minutes at a time. For example, a fast race car might be able to pull off a similar acceleration, but only for a few seconds before it can't go any faster.

Acceleration at liftoff is lower than maximum acceleration during the rest of the launch.

Most of the mass in a rocket is fuel. As the fuel is burned off, the same amount of thrust gets divided over a progressively lower remaining mass.

The Shuttle stack has a mass of 2.03 million kg at launch, and delivers 30.45 MN of thrust. That's 15.0 m/s² of acceleration, or 1.53 g's. (Because it's thrusting vertically, though, it only accelerates upward at 0.53 g's.) This is much lower than the maximum acceleration attained later in flight.