How to speed up the Angular build process

My app took 28secs to build, but I've reduced the time to 9secs. Usings this flag

ng build --source-map=false

you can see the difference in time comparing the time:

ng build --stats-json 

ng build --stats-json --source-map=false

source map is intended only for debugging, Hope it helps

This reduced my build time to 50%

          "optimization": false,
          "outputHashing": "none",
          "sourceMap": false,
          "extractCss": true,
          "namedChunks": false,
          "showCircularDependencies": false,
          "aot": true,
          "extractLicenses": false,
          "statsJson": false,
          "progress": false,
          "vendorChunk": true,
          "buildOptimizer": false,

I've found that for me, this issue was solved by using the watch flag, i.e.

ng build --watch=true

This runs constantly, and automatically builds files only when saved. It has dropped my build time from 8 sec to <1 sec for small changes in code, since it only generates .js files for what actually changed.

From https://angular.io/guide/deployment

The ng build command generates output files just once and does not serve them.

The ng build --watch command will regenerate output files when source files change. This --watch flag is useful if you're building during development and are automatically re-deploying changes to another server.

You should probably use ng build with the necessary options when you are building for production so that the necessary optimizations are completed.