PHP Performance: OPcache, N+1 Queries, and Practical Fixes

Performance problems usually come from: - too many DB queries - heavy loops + slow functions - no caching - no OPcache ## OPcache (big win) OPcache stores compiled PHP bytecode in memory, so PHP does not re-compile every request. Most hosting providers enable OPcache automatically, but it's worth confirming. ## N+1 query problem (classic) Bad: - fetch 50 posts - for each post fetch its author (50 more queries) Fix: - join authors in one query - or fetch all authors in one query and map them ## Quick rule The database should do database work. Your PHP should not do 1000 small queries when 1 query can do it. > Next: Webhooks, accept callbacks from Stripe, PayPal, or other services safely.