Desynch freezes the game allowing it to resynch, this is obvious in a huge number of your "drops".
Same with vsynch enabled, it can't prevent resyching, which the game does a lot.
I have 40ms latency, i play online games for 10 years now, i have never encountered framerate problem or stutter problem that was cause by network latency. Especially i wouldnt except it from game that does only one check on the server and do client calculations locally like Diablo 3.
Problem with Diablo is streaming engine which is awful, it drops fps no matter what settings You get and what limit You apply.
No fps limit, 200-300 fps
180fps limit, frequent drops to 130/140
120fps limit, frequent drops to 80-90
60fps limit, constant drops to 45-50, sometimes to 30.
It constantly drops framerates below Your limit, by 2/3/4 or 10 or 30, not matter how big, it always affect how fluent it feels and even if it do not drop, it still can stutter and its like that since first beta.