Your analysis while good in theory is off in details. Judging by a comparison with a development Perl, map will always be about twice as slow. Probably because of all of the lists you create, then having to internally do the assignments to the hash.

However the slow-down you wondered at with 500 elements is the effect of the quadratic slowdown in my note. The problem is that the entire argument stack was getting moved for each call of the block. The first time that takes work n. The second n-1. The third n-2. etc. So it is quadratic.

If you are willing to recompile Perl, there is a very simple patch available.

---

---

• Are you posting in the right place? Check out Where do I post X? to know for sure.
• Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:

  <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>

• Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
• Want more info? How to link or How to display code and escape characters are good places to start.