If you're in the top five percent of data users on your cellular providers network than the following news about throttling may be of interest to you. Carriers like AT&T and others are apparently implementing measures to limit data usage for their top 5% of data consumers (especially after customers reach the 1 GB/month mark).
The following video by AppAdvice illustrates how data speeds are being adjusted after heavy data use:
Throttled devices upload speeds are similar or unaffected however; download speeds are slowed considerably. The above side-by-side comparison video indicates 2 MB/sec. on a non-throttled device versus .2 MB/sec. on a throttled device. In some cases this renders a device practically useless for downloading.