Slow IPsec VPN Performance, Packet capture "NBSS Continuation Message"????

I've been searching a bunch of threads on the forum, trying to speed up my tunnel and eventually tried some packet captures. When I do a packet capture on the tunnel interface I get a bunch of "NBSS Continuation Message"

Looks like nobody has brought this up on here and googling it doesn't have any good results. Anybody know what this means?