Basics:
1. Ensure that you have not disabled Lua code cache:
https://github.com/openresty/lua-nginx-module#lua_code_cache
2. Load resty.core:
https://github.com/openresty/lua-resty-core#synopsis
3. Check that you are using Redis connection pools:
do not call this: https://github.com/openresty/lua-resty-redis#close
call this: https://github.com/openresty/lua-resty-redis#set_keepalive
4. Use unix sockets instead of TCP sockets if possible (e.g.. Redis is on the same machine)
5. Use Redis pipelines:
https://github.com/openresty/lua-resty-redis#init_pipeline
6. Cache Redis data in OpenResty shared dict and also to Lua module level (preload data in init_*s):
https://github.com/openresty/lua-nginx-module#lua_shared_dict
https://github.com/openresty/lua-nginx-module#ngxshareddict
https://github.com/openresty/lua-resty-lrucache
(there are some projects like https://github.com/hamishforbes/lua-resty-tlc that might come handy).
... and also make look for adjusting Nginx confs and Kernel settings.
