Combining the @ids into a single regex and testing all of them at once is definitely the big win here. The absolute biggest performance gain you can get from the OP's posted code is to fix it so that each file is only read once instead of re-reading it for each id.

If you're dealing with a lot of ids and the single combined regex starts slowing down unacceptably, take a look at Regexp::Assemble for a way of building reasonably efficient regexes which check for a large number of target patterns in one shot. I've used it for up to ~500 target words/phrases at a time and I see no reason why it shouldn't perform well with much larger target sets.

In reply to Re^2: faster way to grep by dsheroh
in thread faster way to grep by coldy

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.