This is one of the warnings to keep in mind when purchasing an iPhone on Verizon. One, you’ll get a better network, but with slower data speeds. Two, if you use a lot of data, those slower data speeds will get slower. Yeah.
As Verizon puts it, this only applies to users that use an “extraordinary amount of data”, and are in the top 5% of Verizon data munchers. Once that once that throttling is in motion, it will remain in effect till the end of the monthly billing cycle. For a full understanding of what is going on here, including how file formats would be affected, hit up the source link, peeps. Via: Verizon (PDF)