Runtime performance is very slow compared to native Angular testing

[antch]

In my project, there are a few problematic component tests that occasionally creep past the 5s limit and cause Jasmine to fail awaiting the result of shallow.render().

One such component has 9 tests that take between 14-17 seconds to execute with shallow-render using Jasmine spies. When changing it to use TestBed.configureTestingModule with the same spies, directly accessing fixture, the 9 tests take less than one second.

I also just quickly refactored a component test that renders a chart from shallow-render to native Angular testing, and the runtime decreased from around 1.4 seconds to 0.18s.

Is this type of rendering performance discrepancy expected?

Edit: I created a gist to illustrate this, based off of a fresh ng new project with the default spec deleted: https://gist.github.com/antch/cc792661d0e9e2c9ce7801856ad01ed6

The only added dependencies are chart.js and primeng.

You can comment out each describe block to see the huge disparity in execution time.