The following is the `perf top` output of blue's CPU2 (which has been made to handle both tb0 and eno1) when idle (no iperfs running through it).

   PerfTop:      55 irqs/sec  kernel:94.5%  exact: 100.0% lost: 0/0 drop: 0/0 [4000Hz cycles:P],  (all, CPU: 2)
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

     2.66%  [kernel]       [k] menu_select
     2.17%  [kernel]       [k] cpuidle_enter_state
     1.72%  [kernel]       [k] _raw_spin_lock
     1.39%  [kernel]       [k] ktime_get
     1.34%  [kernel]       [k] read_tsc
     1.29%  [kernel]       [k] native_write_msr
     1.27%  [kernel]       [k] __hrtimer_next_event_base
     1.27%  [kernel]       [k] sysvec_apic_timer_interrupt
     1.21%  libc.so.6      [.] malloc
     1.21%  [kernel]       [k] kmem_cache_free
     1.07%  [kernel]       [k] psi_group_change
     1.06%  [kernel]       [k] select_task_rq_fair
     1.01%  [kernel]       [k] native_sched_clock
     0.99%  [kernel]       [k] account_idle_ticks
     0.98%  [kernel]       [k] do_idle
     0.97%  [kernel]       [k] __hrtimer_run_queues
     0.97%  [kernel]       [k] schedule_idle
     0.96%  [kernel]       [k] rb_next
     0.90%  [kernel]       [k] tick_program_event
     0.89%  [kernel]       [k] note_interrupt
     0.85%  [kernel]       [k] update_sd_lb_stats.constprop.0
     0.84%  [kernel]       [k] tick_nohz_next_event
     0.83%  [kernel]       [k] intel_iommu_map_pages
     0.83%  [kernel]       [k] cpupri_set
     0.82%  [kernel]       [k] __irq_wake_thread
     0.81%  [kernel]       [k] tcp_rcv_established
     0.78%  [kernel]       [k] __netif_receive_skb_core.constprop.0
     0.78%  [kernel]       [k] tcp_do_parse_auth_options
     0.73%  [kernel]       [k] iwl_pcie_rx_handle.cold
     0.73%  [kernel]       [k] alloc_iova_fast
     0.70%  [kernel]       [k] __schedule
     0.69%  [kernel]       [k] dequeue_task_rt
     0.69%  [kernel]       [k] _raw_spin_unlock
     0.69%  [kernel]       [k] update_rq_clock
     0.68%  [kernel]       [k] tick_nohz_idle_got_tick
     0.68%  [kernel]       [k] ieee80211_data_to_8023_exthdr
     0.67%  [kernel]       [k] sched_balance_update_blocked_averages
     0.63%  [kernel]       [k] __wrgsbase_inactive
     0.62%  [kernel]       [k] cpuidle_not_available
     0.61%  [kernel]       [k] clflush_cache_range
     0.60%  [kernel]       [k] __switch_to_asm
     0.59%  [kernel]       [k] ip_rcv_finish_core
     0.59%  [kernel]       [k] ieee80211_rx_handlers
     0.59%  [kernel]       [k] __update_load_avg_cfs_rq
     0.59%  [kernel]       [k] update_load_avg
     0.59%  [kernel]       [k] napi_complete_done
     0.59%  [kernel]       [k] dma_pte_clear_level