Enable gzip for the JSON changelog/index responses in the nginx vhost (the mod
.jar/.zip files are already compressed — do not gzip them):
gzip on;
gzip_types application/json;
gzip_min_length 1024;
Conditional GET (ETag/If-None-Match → 304) is already supported by nginx's
default static handling; the launcher sends If-None-Match and caches the body.