Reproduction steps:

1. Open "MinimalRepro.zip" project
2. Open the "Test" scene
3. Open the Profiler Window
4. Enter Play Mode
5. Select the First Frame
6. Search for "Start"
7. Compare the "Time ms" of "Vector2Test.Start()" and "Vector3Test.Start()"

Expected Result: "Vector2" and "Vector3" "Distance" function should execute at a similar time
Actual Result: "Vector2" "Distance" function is slower than "Vector3"

Fixed in: 2019.2.0a4, 2019.1.0a6

Reproduced with: 2019.1.0a5, 2019.1.0a1, 2018.3.0b7, 2018.2.14f1
Did not reproduce on: 2019.1.0a6, 2018.1.9f1 (Couldn't find the scripts in the Profiler)