Angular 6 vendor and main js scripting size decrease

问题

I'm using angular 6+ while npm start project in local system it's take above 12 seconds to perform application .

When initial load page vendor and main js file size too big so how could I reduce size?.

1.I tried to remove style in my html code. 2. Removed un-necessary import class.(Angular)

Package.json:

/  "devDependencies": {
    "@angular-devkit/build-angular": "^0.8.8",
    "@angular/cli": "^6.2.8",
    "@angular/compiler-cli": "^6.1.0",
    "@angular/language-service": "^6.1.0",
    "@types/jasmine": "^2.8.14",
    "@types/jasminewd2": "~2.0.3",
    "@types/node": "~8.9.4",
    "codelyzer": "~4.3.0",
    "jasmine-core": "~2.99.1",
    "jasmine-spec-reporter": "~4.2.1",
    "karma": "~3.0.0",
    "karma-chrome-launcher": "~2.2.0",
    "karma-coverage-istanbul-reporter": "~2.0.1",
    "karma-jasmine": "~1.1.2",
    "karma-jasmine-html-reporter": "^0.2.2",
    "protractor": "~5.4.0",
    "ts-node": "~7.0.0",
    "tslint": "~5.11.0",
    "typescript": "~2.9.2"
  }

angular.json

   "optimization": true,
              "outputHashing": "all",
              "sourceMap": false,
              "extractCss": true,
              "namedChunks": false,
              "aot": true,
              "extractLicenses": true,
              "vendorChunk": false,
              "buildOptimizer": true
            }
          }
        },

来源：https://stackoverflow.com/questions/53882154/angular-6-vendor-and-main-js-scripting-size-decrease