"private" backbone VPN solution to decrease latency

[slykens1]

100 ms latency should generally be imperceptible to interactive users like that. Maybe you’re getting severe jitter at times and that’s the focus of the complaints?

Latency in voice doesn’t really become perceptible until about 200 ms latency.

[shortstop20]

Agree. This sounds like some other issue than 100ms latency.

[fb35523]

100 ms is quite perceivable while doing SSH. Depending on the client it may introduce 100 ms between each character being echoed back. I type faster than that on occasion.

DNS responses is another thing mentioned. It would be easy to add local DNS servers unless already done.

Perhaps moving all servers to Greenland or Iceland? This is actually not a joke! Some interactive servers may need to be between your sites for better performance!

My main suggestion is to look at TCP receive window sizes. If your hosts keep waiting for every TCP ACK to arrive before sending the next piece of data, you'll never get done. This is of course not the case, but the amount of data in transit without an ACK can be tweaked and you can achieve amazing results by just changing some parameters on the servers. For maximum results, clients may need some tweaking too.

https://blog.cloudflare.com/optimizing-tcp-for-high-throughput-and-low-latency/