Please, run nat64-expire-worker-walk only when NAT64 is configured in VPP to avoid possible performance degradations when it is not needed. We got following data when run L2BD performance test in CSIT:

Thread 1 vpp_wk_0 (lcore 2)
Time 10.7, average vectors/node 187.57, last 128 main loops 16.50 per node 140.80
vector rates in 1.0572e7, out 1.0572e7, drop 0.0000e0, punt 0.0000e0
Name State Calls Vectors Suspends Clocks Vectors/Call
TenGigabitEtherneta/0/0-output active 320728 56590687 0 9.31e0 176.44
TenGigabitEtherneta/0/0-tx active 320728 56590687 0 4.35e1 176.44
TenGigabitEtherneta/0/1-output active 323107 56590625 0 9.67e0 175.15
TenGigabitEtherneta/0/1-tx active 323107 56590625 0 4.29e1 175.15
dpdk-input polling 324222 113181312 0 6.12e1 349.09
ethernet-input active 595330 113181312 0 2.04e1 190.12
l2-fwd active 595330 113181312 0 2.07e1 190.12
l2-input active 595330 113181312 0 2.41e1 190.12
l2-learn active 595330 113181312 0 2.17e1 190.12
l2-output active 595330 113181312 0 1.55e1 190.12
nat64-expire-worker-walk interrupt wa 2 0 0 1.48e3 0.00