18. ab Siege Apache Flood Memtrack XHProf GUIMark Hardinfo Bonnie++
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Editor's Notes
Websites have more pages than you think. Performance effects are aggregate.
Database Buffer Cache Network etc
Overloaded databases Badly configured machines NFS / File system contention Solutions: Get a real system administrator Pick the right database for the job Clustered / Proxy databases
Missing indexes. Poor schema architecture. Bad database tuning. Selecting too many columns / rows
Proxy callout to external services Remote PHP includes REST / AJAX SOAP / RPC calls Solutions: Cache the network calls Design your AJAX so you can easily cache it
Image manipulation Encryption system/exec/etc. function calls Solutions Off load work to other machines Gearman and similar are your friends
Performing extensive looping text replacements Performing extensive looping in general Badly written Regular Expressions Extensive recursive functionality
