Not necessarily an Internet issue. I was having issues with my frames freezing in both SP and MP, but more often in MP. Everybody kept telling me it was my Internet connection. Turns out I was getting high response times from DCS reading from my TEMP folder and pagefile at the same time. Moving one to another hard drive fixed my issue even though both were initially on an SSD. Samsung 840 Pro, 256 GB with 8 GB of DDR 1333 RAM. Moving up to DDR 1600 16 GB didn't fix it but reduced the frequency at which it was happening.
Edit: I should mention that everything was at stock speeds. No overclocking or memory timings were adjusted.