Huge amounts of tests have a start delay when pressing "Run All" in the Test Runner

Reproduction steps:
1. Open the attached "repro_IN-53943_SmallAmountOfTests.zip"
2. Go to "Window > General > Test Runner" and press "Run All"
3. Observe how much time it takes for the tests to start running when the project doesn't have a lot of tests
4. Open the attached "repro_IN-53943_LargeAmountOfTests.zip"
5. Open the "Test Runner" window and press "Run All"
6. Observe how much time it takes for the tests to start running when the project has a lot of tests

Expected results: There is no difference in the test launch time no matter how many tests the project has
Actual results: There is a difference in the test launch time no matter how many tests the project has

Reproduced with: 2021.3.31f1, 2022.3.10f1, 2023.1.16f1, 2023.2.0b12, 2023.3.0a8

Reproduced on: Windows 11 (10.0.22621) (user's), Windows 10 (22H2)
Not reproduced on: No other environments tested