Initially reported in https://github.com/angular/angular/issues/26674#issuecomment-443263655 by @sod --- hm indeed, just updating ngtools gives me the slowdown. Also using angular 7.1 with old ngtools 7.0.7 is significantly faster. versions | 1st run | 2nd run | 3rd run | 4th run | 5th run -|--|--|--|--|- `@angular 7.0.4, @ngtools 7.0.7` | 31s | 15s | 7s | 5s | 5s `@angular 7.0.4, @ngtools 7.1.0` | 29s | 14.5s | 15.5s | 12s | 12s `@angular 7.1.1, @ngtools 7.1.0` | 29s | 13.5s | 13.5s | 15s | 16s `@angular 7.1.1, @ngtools 7.0.7` | 28s | 12.8s | 7s | 5s | 4.2s