What is the best approach to add custom javascript with Hugo Zen Theme

Hi, this is not a problem, I am trying to find out the optimized way to do the task.

I think some of you are using Hugo Zen theme. I am using that theme for one of my website.

Can you share your experience the best approach to integrate custom javascript to Zen Theme? And also any specific file you added any javascript?

Right now, what I found after applying my custom javascript the build time degrade a lot compared to before I add those javascript.

If anybody has any suggestion plz advice.

If you share the link to your repo so we can see the code it will be far easier to help you.