Lepton can decompress significantly faster than line-speed for typical consumer and business connections. Lepton is a fully streamable format, meaning the decompression can be applied to any file as that file is being transferred over the network. Hence, streaming overlaps the computational work of the decompression with the file transfer itself, hiding latency from the user.
In my humble opinion, dropbox's image gallery webapp is considerably faster than any other I've seen, especially when compared to imgur.
> I don't think they're compressing this and decompressing it client side.
The speed quotes made it sound like client-side was a concern. Why would you go to all the effort of devising a new image compression format saving 20%+ storage and on the wire, and not have it decompressed client-side, especially when you control the client?
My rough understand, as someone who works at Dropbox and knows some of the people who worked on this (but isn't directly involved), is that this currently only runs on our servers. The perf requirements are primarily that we don't want to slow down syncing / downloads significantly - and also want to keep the CPU cost under control. As is, the savings in storage space should easily pay for the extra compute power required.
The typical encoding/decoding rates are measured with a Xeon... my guess is that lower powered phones/netbooks will be considerably slower. I'd trade off a 20% longer sync time in exchange for not running my laptop battery down.
You're correct ofc, download costs = 10 months of storage.