(Bisection found and) perf verify confirmed the guilty change, details there [0].

The most notable difference is in ip6-lookup graph node getting ~257 of "Loads blocked due to overlapping with a preceding store that cannot be forwarded.".

[0] https://gerrit.fd.io/r/c/vpp/+/35748/4#message-5f67ef777797143d8778ddd37e1b000d07ca2b9a