Performance Tuning

lspci – validate your slot setting for each NIC
lspci -v -v -s 09:00.0
09:00.0 Ethernet controller: 10GbE Single Port Protocol Engine Ethernet Adapter
< truncated >
Capabilities: [58] Express Endpoint IRQ 0
Device: Supported: MaxPayload 4096 bytes, PhantFunc 0, ExtTag+
Device: Latency L0s <64ns, L1 <1us
Device: AtnBtn- AtnInd- PwrInd-
Device: Errors: Correctable- Non-Fatal- Fatal- Unsupported-
Device: RlxdOrd+ ExtTag- PhantFunc- AuxPwr- NoSnoop+
Device: MaxPayload 128 bytes, MaxReadReq 512 bytes
Link: Supported Speed 2.5Gb/s, Width x8, ASPM L0s L1, Port 0
Link: Latency L0s unlimited, L1 unlimited
Link: ASPM Disabled RCB 64 bytes CommClk- ExtSynch-
Link: Speed 2.5Gb/s, Width x4
Vector table: BAR=4 offset=00000000