Your network and storage teams have decided to disable flow control on all host, switch, and NetApp interfaces, both 1 Gb and 10 Gb, to increase performance. Why does this action increase performance?

MTU defines the maximum frame size for a network interface and provides no congestion control mechanism whatsoever; it plays no role in managing network congestion.

The host-side MTU, like any MTU setting, defines packet size limits only and does not function as a congestion control mechanism on either side of the connection.

Ethernet flow control (IEEE 802.3x) uses PAUSE frames to halt all transmission on a link when buffers fill, causing head-of-line blocking that degrades throughput across all flows indiscriminately. When flow control is disabled, upper layer protocols such as TCP use their own per-flow congestion control algorithms - including sliding window adjustments and selective acknowledgment - to manage traffic more granularly, which reduces unnecessary pauses and improves overall network and storage performance.

Lower layer protocols such as Ethernet implement flow control via PAUSE frames - disabling flow control explicitly removes lower layer congestion handling, which is the opposite of what this answer claims.