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Found one definition

1.                 From The Jargon File (version 4.4.7, 29 Dec 2003):
                   
   
   
                   
                     
   tense
    adj.
       Of programs, very clever and efficient. A tense piece of code often got
       that way because it was highly tuned, but sometimes it was just based on a
       great idea. A comment in a clever routine by Mike Kazar, once a
       grad-student hacker at CMU: “This routine is so tense it will bring tears
       to your eyes.” A tense programmer is one who produces tense code.