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The datasheet quotes 200ns for the L2-only FM2000, 300ms with ACLs enabled for the FM3000. Arista quotes 600ns delay regardless of packet size for their 24-port switches and 1200ns for their 48p version, which uses an internal fat tree of 6 24p FocalPoint chips (so 3 300ns hops are req'd).
The PHY can also add quite a bit of delay; supposedly 10GBase-T transceivers, due to the block encode/decode delay, add 1us per link (Wikipedia). Fiber, CX4, and twinax should be much lower-latency, since they escrew the fancy coding techniques for lower-error cabling. This is something I'd like to measure with the Triumph box coming soon.