Yes! Years ago, processor speeds evolved slowly enough that it was practical for game developers to write all animation delays in their games something like this:

    for (i=0; i<400; i++) ;

They would test their delay value and then increase their loop count as necessary. This was a lot easier than doing clock-based delays. I'm not sure how it was on Windows/DOS at the time, but around the same era on MacOS, you couldn't even get millisecond accuracy without a lot of effort. The standard time unit on a Mac then was the tick, or 1/60th of a second, and some things didn't look too nice at tick granularity.

So this kind of time delay in games and other software was common practice. When processors did start getting significantly faster, some games became unplayable or bugged out altogether.

Along came the turbo button: it didn't actually make your computer faster, it made it slower. Because of the confusing name, the turbo button was usually rigged so that you would leave it on by default -- using your processor's manufactured clock speed -- but if you wanted to play an older game that relied on processor speed for delay timing, you would deactivate the turbo, slowing your system clock speed down to something that matched older hardware.

Absolutely, it did change the clock speed of the processor (back then measured lower double-digit MHz/Megahertz).