I tend to use LL HLS, because that is the best setting for most streaming websites. Could be a lot of things why MFC looks like dog shit.
1. could be the Cam model who is using a VPN while streaming. Can cause latency issues, Some VPN services have bandwidth limits or throttling that can reduce internet speed.
2. I won't get all geek squad on you, but MFC uses TCP protocol for their streams which is fucking stupid, while Twitch, Youtube, and I assume CB uses UDP protocol for their stream.
3. Servers from 8-10 years ago, bad scalability, not enough bandwidth
Hopes that answers your question