Angular: Does Karma have to compile all my code every time I run `ng test`?

Every time I run ng test in my (fairly standard) Angular 8 project with Jasmine and Karma, I find that Karma builds all of my code before tests start running in the launched browser.

Is there a way for me to tell Karma to only build code that has changed from the last time I ran ng test? Or some other mechanism for shortening the time between changing my code and seeing the results from my tests with Karma?