I understand you are feeling your tests are running slowly.
There are so many factors that makes tests to run slowly. I have a doubt if downloading the images is the sole reason of your problem.
For example, my previous experiences tell that “Log Viewer” makes my test very slow.
Or how fast your network connection to the Internet is? For example, my home Wifi has usually 9Mbps (not fast but enough for me). If you have LOTS of image downloading and your network is too slow, the test will run slow. Yes. Naturally. Then you should move your test to some Cloud environment (Amazon, GCP) where you will enjoy 10 times broader network connections.
How often your test script opens & closes Chrome browser? Only once per 1 execution of entire your tests? or does your test repeat opening+closing browser many times?
Repeating to open&close browser will slow down your test significantly. You should reuse 1 connection from KS to browser as much as possible for faster response. But why? One reason is that Katalon Studio starts a browser with a default User profile. A default User profile has the browser’s cache on local disk empty. No image, no css, no js, no HTML is cached in the local profile folder. Empty cache requires downloading all of required images, all css files, all javascript referred by the page. Therefore a request from a browser with the default Profile will be inevitably slow. But if you keep a browser open and reuse it many times, the browser’s cache will help browser to respond faster.
If you could use the browser’s local cache effectively, it works the same as “disabling image downloading”.