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  Reading CONSTANTS versus Global Variables
Constants x 1.91 faster 0.0011 Globals 0.0021
  + vs += integer operators
+ integer x 1.05 faster 0.0021 += integer 0.0022
  + vs += string operators
+ strings 0.0038 += strings x 1.03 faster 0.0037
  += vs + string operators
+= strings 0.0039 + strings x 1.03 faster 0.0038
  short vs long variable names
short var name (1 char) x 4.00 faster 0.0008 long var name (72 chars) 0.0032

Testing PHP 4.3.3 Completed on Linux. Benchmark done on: 01-Mar-2004 12:36:04

(c) 2003-2004 John Lim PHP Benchmark Suite (PHP BS 1.0).