19. Disable DB logging(syslog)
Reduce 404 Errors
Fast 404 Responses
Client Side Validations
Compress Image and lazy loading
Use CSS Sprites
20. Use Devel Module to watch queries
Rewrite Views Queries/Avoid Views
XHProf
Hhvm, FPM, APC
DB Profiling and Tuning
21. Use Boost, don't Boot-strap DB
If your cache tables are huge
use memcached
Use Reverse Proxy Server
Use heiuristing Cache Clearing
Implement Cache Warming