There are several ways we can improve the Maps app's ability to upload GeoJSON files, some on the Maps side, some on the File Upload side. Some of these should be deemed more critical than others and are noted as such. This is a tracking issue to cover them.

• Fix issue on Maps side copying entire feature collection as part of layer descriptor (critical) ([Maps] Add 'InjectedData' class and revise so File Upload Features are assigned to new InjectedData instances #46381)
• Chunk file on parse to prevent blocking of thread (originally identified here) and browser freeze (critical) ([Maps][File upload] Parse geojson files in chunks to avoid thread blocking #46710)
• If possible, consolidate common logic between chunking operation used for chunked json parsing and chunking used to send data to ES from Kibana File Upload
• Cap preview at 100MB
• Consider memory optimization that deletes chunks after each is processed (may or may not be possible as we still have to deliver it to be indexed following preview)
• Increase File Upload limit and Chunk limit (size TBD) (Make configurable?)
• Revise File Upload to allow consuming applications to subscribe to chunked delivery (nice to have)
• Update Maps app to allow adding layers in chunks. This is currently blocked by not having an accurate indicator downstream from mapboxgl indicating when the first layer chunk has been completely added. Connect to File Upload chunked delivery (nice to have)