Yep, I have heard such stories. "Folks" were FPGA engineers and one of their primary target was to be able to cache "stuff" in SRAM as much as possible as that is the part which yields nanosecond latency.
My experience was more along the "man in the middle" setups which HFT shops used to hide their trading in the shorter term. The man in the middle got better prices at the exchange due to increased volumes and the HFT shop got a fairly good opportunity to hide it's activity for a short while.
At a later stage at some venues, the HFT shop did not even need to route their orders via MITM, the MITM simply got a firehose of HFT's execution reports to reverse build the order books !
My experience was more along the "man in the middle" setups which HFT shops used to hide their trading in the shorter term. The man in the middle got better prices at the exchange due to increased volumes and the HFT shop got a fairly good opportunity to hide it's activity for a short while.
At a later stage at some venues, the HFT shop did not even need to route their orders via MITM, the MITM simply got a firehose of HFT's execution reports to reverse build the order books !
Smoke and mirrors...(and nonsense)