[henrixd]

I would expect large majority to have a decent fixed price data packages. However there are people that have slow speeds and/or expensive metered data plans, so I wouldn't get too frisky. Overall bandwidth is usually the bottleneck, so yes.

[chintan39]

I am building a chat application(http://tiny.chat) that will use less bandwidth. Is it worth optimizing reduce as many bytes as possible? Or the end user doesn't care if there are couple of extra KB used?

[hanyoon]

A couple KB shouldn't make much of a difference. If your app explodes in popularity, then yes, you should make every effort to optimize.

[chintan39]

My question is does the average joe care if app is using less bandwidth or it doesn't matter.

[hanyoon]

To be honest, for a couple KB's worth of difference, probably not. But I'd assume it'd be good practice to optimize the best you can regardless.