Hi,
Could you provide more details on the nework infrastructure.
1) SEPM version details
2) Total number of SEP clients and version details
3) WAN link if any & Bandwidth size, Number of clients over the WAN link
4) Is there any GUP?
5) Client heartbeat communication settings, Push or Pull?
6) Number of Content revisions stored at SEPM?
Generally SEPM will provide clients delta updates unless clients request full.zip. If there is sudden increase in the network consumption then need to monitor actual traffic.