When WebView windows are loaded (Services, Getting Started, etc.), one of computer's cores becomes heavily loaded.

Steps to reproduce:
1) Launch Unity.
2) Monitor CPU usage via 'System Monitor' app.

When Unity is at project selection screen, CPU usage on one of available cores is very high, compared to others (100% on mid-end PC). The high usage alternates between the cores every ~10 seconds. This is most likely caused by the 'Getting Started' section, which is a WebView. When selecting a project to open (Nautilus window takes focus from the project selection window), the CPU usage returns to normal. The same issue occurs when Services or other web windows are open within the Editor.
This does not occur on macOS or Windows.

Reproduced on:
5.2.2f1, 5.3.6f1, 5.6.0b8