Reduce data usage

[nop33]

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[nop33]

The high data usage might be related to NFTs. The user that reported this said that they used their mobile wallet for 6 minutes and had 1GB of data usage. They have around 40 addresses with 40 NFTs with "nothing crazy".

Ideas discussed on Slack:

• Check file size before loading EDIT: Done ✅
• Don’t load if too big, show an info label near / on the NFT (to be designed). EDIT: Done ✅
• User can decide to manually load the file by tapping on the image. EDIT: Done ✅
• Once loaded, compress the file locally, and cache it (in general, cache all NFT files, except if too big, see below)
• Maybe don’t cache if size cannot be reduced to less than a certain number (say, 10mb).
• On next app load, use cached files.

cc @mvaivre