Do you need to always displaying up-to-date data on graph?
If not necessary, what you may consider is... stream your data to file during acquisition. Read, up to the last saved data, file and update the graphonly when user click on a "Update Graph" button...
Just a quick though because I used such way in one of my many years back project; a project that records battery discharging profile, which reads voltage level every 2 sec for days.
Others may have better suggestion 😉
