TSO really turbocharged bulk TCP transfers, so now 2 GHz can drive 10 Gbps as long as you're sending >=64KB chunks. This has made performance brittle, because 10 Gbps of small packets requires 10x-100x as much CPU as 10 Gbps of bulk traffic. Also, receiving requires more cycles than transmitting.
Indeed, it's common to see DDoS protection offerings defined both in throughput (e.g. 50 Gb/s) and packets per second (e.g. 30 Mpps), which results in a bottleneck in packet size (e.g. ~200 bytes) at high throughput.
