You can either:

- have the SFU (videobridge) in a more "central" location

- have multiple videobridge installations (cascaded bridges) where required with a low latency interconnect (its effectively a smart relay).

- you could use geographically distributed forced TURN servers with low latency interconnect to the SFU, but it would be more bandwidth intensive, and not really useful unless you truly have a REALLY low latency interconnect.

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Reducing the quality of the streams may also help, if it is bandwidth that is the constraining factor.