improve layer rendering performance for existing and uploaded layers

[gubuntu]

From @gubuntu on May 12, 2017 10:8

From @gubuntu on January 22, 2017 9:55

in order of priority:

• parallelise rendering with multiple QGIS backends
• pre-seed on upload
• file compression
• optimise file formats
• optimise Cloudflare CDN
• optimise resolution / resampling / vectorising (done in 4.1...)
• moving vectors to PostGIS?

Copied from original issue: kartoza/geosafe#33

Copied from original issue: kartoza/geonode#218