Cache the bytecode
Bytecode (called opcode for PHP) is the binary code generated from the source code. Some accelerators are able to cache bytecode, which avoids needing to recompile it from the source code every time. Less time spent compiling equals less CPU and RAM used.
Minify JavaScript files
Use a tool such as YUI Compressor to:
- remove unnecessary white spaces
- remove unnecessary line breaks
- remove unnecessary semi-colons
- shorten local variable names