Steps to reproduce:
1. Download net fiddler app https://jagt.github.io/clumsy/
2. Open it and set Lag to something like 500-1000 and start the app on "localhost ipv4 all"
3. Try to open any Unity project
4. After you choose a project, Unity will open in a buggy fashion or outright freeze/crash

Expected: Unity opens normally without any influence of localhost traffic/lag
Actual: Unity gets affected, frozen or buggy when localhost is laggy

Reproduced on: 2017.2.0b2, 2017.1.0f2, 5.6.2p2, 5.5.4p1