How to reproduce:
1. Create a new project in your prefered workspace
2. Open and connect it to Perforce
3. Create a new folder and in it create a 100 new materials (Just copy and pasting the same default material is fine)
4. In the Hierarchy Window select them all and delete them
5. Observe how long it takes until they're fully deleted

Expected result: the files are deleted relatively fast (3-10 secs)
Actual result: the deletion of the files is slow while VCS is enabled (40~secs)

Reproduced in: 2019.3.0a11, 2019.2.1f1, 2019.1.14f1, 2018.4.6f1, 2017.4.31f1

Note: Reproduces both with Plastic SCM and Perforce