First you need to identify the cause of your latency. The two common causes are congestion on interfaces (such congestion actually more likely to cause drops, which often causes app "latency"), the second cause being distance based latency (also seen, by users, as app "latency").
Once you've identified the cause(s) of latency (and/or drops), you can sometimes remediate the problem.
Of the two principal causes, dealing with distance based latency, can be very difficult, even sometimes impossible, to remediate.
BTW, at an international company, I worked at years ago, this was an on-going issue. I.e. "what's wrong with the network"; users in same city as DC report application works fine, but those on the other side of the world (literally) report application performance is horrible (to same DC). (Also, BTW, buying more bandwidth doesn't solve the distance issue.)
