CGI.pm considered painful and ugly.

HTML generating methods considered very slow.

td and Tr considered hard to read.

Nested maps considered harmful for maintainer's brain.

Considering considered a waste of time :)

But I think you're not thinking of ever maintaining this code anyway. The one-letter variables (typing "key" instead of "k" will not give you RSI), big indentation levels, hardcoded colour codes and sequential building of HTML give that away. I'm guessing that somewhere in your code is something like $html = read_file('header.html');, or worse: $html = $q->start_html; (if it is a string literal, please let someone strangle you).

Just store your data as an array of arrays, or something alike, and use a simple module to write the table for you. Or at least move the html-generating things out of the way of anything that deals with raw data.

Templating modules considered mandatory.