Reproduction steps:
1. Create a new Unity project
2. Enter Play Mode
3. Open Profiler
4. Observe the Profiler

Expected result: No lag spikes, Semaphore.WaitForSignal in Profiler call time is low (under 3.0ms)
Actual result: Constant lag spikes, Semaphore.WaitForSignal in Profiler call time is high (above 10.0 ms)

Reproducible with: 2018.4.30f1, 2019.4.17f1, 2020.1.17f1, 2020.2.0f1, 2021.1.0a9

Notes:
- On 2018.4.30f1 when spikes occur there is no Semaphore.WaitForSignal instead there is Gfx.WaitForPresent and call time is lower but still high (above 5.0 ms).
- The issue reproduces not on all Mac machines.
- When Maximize on Play is enabled, the issue is even more clear to see
- High call time keeps stable in different versions of Unity (doesn't decrease or increase)

Tested machines:
- MacBook Pro (16-inch, 2019), macOS 10.15.3, call times of 11-15ms (Reproduced)
- MacBook Pro (16-inch, 2019), macOS 11.1, call times of 10-14ms (Reproduced)
- iMac (Retina 5K, 27-inch, 2017), macOS 10.15.7, call times of 12-13ms (Reproduced on macOS, no reproduction on Windows)
- MacBook Pro (15-inch, Mid-2015), macOS 10.15.6, no spikes and call times under 1ms (Didn't reproduce)