Handsets can mitigate this by prioritizing the IPsec traffic internally to a different WMM class (such as AC_VO). This also requires rest of the subscriber's network (if it's not wholly integrated as in most home WiFi routers/access-points) knowing how to take such traffic and prioritize it over other bulk/latency-sensitive traffic.
Handsets can counteract this by focusing on IPsec traffic internally to a different Quality of Service (QoS) class (such as AC_VO). This also necessitates the rest of the subscriber's network (if it is not entirely integrated, like most home WiFi routers/access-points) being aware of how to handle such traffic and prioritize it over other bulk/latency-sensitive traffic.