In single player I have no issues at all. I have a very mid-range system, or should I say low-end?:
Dell Core i7-4790 3.6 GHz 12 GB RAM with a Geforce GTX 745 4GB Windows 10 Home 1709
I fly it 2560*1440 medium + deferred shading with no stutters and smooth workings, even when I do missions with the MOOSE framework.
It works even better on my portable, a Dell XPS 15 9550 16 GB i7-6700HQ 2.6GHz Win 10 Pro 1709 with Intel graphics 530 + Nvidia GTX 960M 8 GB, which I run 1920*1080 in High settings + deferred shading.
I find the performance on both machines in single player better than DCS 1.5