Tor Browser stalls while loading Facebook login page (Waiting for static.xx.fbcdn.net)

Problem: After opening the Tor Browser and typing in facebook.com, page loading hangs, status bar showing "Waiting for static.xx.fbcdn.net"

HTTP GET requests for small images from static.xx.fbcdn.net stall in the "Blocked" state for minutes - viewed in Developer tools / Network / request / Timing (see attached screenshot Step2.png).

When a different website is opened in a new tab, HTTP requests continue loading successfully - seems to be some livelock within the browser.

This is not a network issue, connectivity in the browser works fine, also verifed without a SOCKS proxy (direct connection without Tor).

Reproducibility: nearly 100%

Environment:

• Windows 10 Pro, 64bit
• Tor Browser 7.5.3 for Windows, english
• Tor Browser 8.0a5 for Windows, english

Trac:
Username: uzi