"HFT" means different things to different people.
I've worked at places where ~5us was considered the fast path and tails were acceptable.
In my current role it's less than a microsecond packet in, packet out (excluding time to cross the bus to the NIC).
But arguably it's not true HFT today unless you're using FPGA or ASIC somewhere in your stack.
loading story #47390864
The one person who understands HFT yeah. "True" HFT is FPGA now and also those trades are basically dead because nobody has such stupid order execution anymore, either via getting better themselves or by using former HFTs (Virtu) new order execution services.
So yeah there's really no HFT anymore, it's just order execution, and some algo trades want more or less latency which merits varying levels of technical squeezing latency out of systems.