What is best TCP throughput benchmarking tool?

[Lev Serebryakov]

 I need to benchmark different endpoint (not router) network performance
with different encapsulations (if_gre, if_gif) and with/without IPsec
(including if_ipsec).

 What is suitable traffic generator/receiver for me?

 I'm trying to use benchmarks/iperf3, but it consumes questionable
amount of CPU in several cases and maybe benchmark becomes limited by
user-side CPU consuming, which is bad.

 I've tried "benchmarks/netperf" — it hangs with non-default window size.

 I've tried "benchmarks/netperfmeter" — it doesn't work without SCTP in
kernel.

 Please note, that I'm testing endpoint, not a router, so netmap-based
packet generators & receivers is no use for me, unfortunately.

-- 
// Lev Serebryakov