For those that have limited drive space or just want to conserve storage space, enter about:config in the address bar and set toolkit.telemetry.unified to false. This will prevent IceDragon v42 from creating and storing telemetry-ping files in the profile folder. Each file is about 17 to 18 KB and can add up quickly over time depending on how many sites are visited.
I could be wrong, but I couldn’t find any evidence that the telemetry-ping data is being sent anywhere. The following entries in about:config would have to be set to true to allow it: toolkit.telemetry.archive.enabled
and IceDragon’s default settings are false for these two items.
Also, there are no datareporting policy settings in about:config such as: datareporting.policy.dataSubmissionEnabled &
datareporting.policy.dataSubmissionEnabled.v2 as they are in Firefox, although I haven’t checked Firefox to be sure.
Also, Firefox has telemetry settings in the Options window that are not present in the IceDragon Options window.
Finally, if you enter about:telemetry in the address bar and check the settings section, it shows that telemetry Enabled is set to false. See image1 and image2 below. I should point out that everything will be greyed out (you won’t see any of the info shown in the images below) if you have already changed toolkit.telemetry.unified to false in about:config and restarted IceDragon. You will need to change it back to true and restart IceDragon if you want to see the info.