If you're using a Unix-like system, one option is the system time command, which (unsurprisingly) times how long it takes for a command to execute. For example, to time how long it takes the wc command to process the system dictionary:

    $ time  wc /usr/share/dict/words
      45427   45427  409305 /usr/share/dict/words
 
    real    0m0.232s
    user    0m0.170s
    sys     0m0.010s
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You can use the same technique to time your scripts, provided that you can execute them from the command line.

Cheers,
Tom