If you're feeling ambitious, which it sounds like you are, you can always compact your data before sending it. Consider using pack() on your data to reduce the size, and then possibly MIME encoding it to handle the encoding for the URL. Base64 is good for your application since it is fully e-mail compatible.

UTF-5 is also a possibility, and it is used to "encode" UNICODE for DNS purposes, mapping two-byte characters into the very limited DNS space A-Za-z0-9-. Fortunately, there is a little more "bitwidth" in the URL specification, something that could be better exploited with careful analysis and testing.

Instead of having a parameter like "mode=view" or "mode=edit", consider using an ENUM() type parameter, where you have a table of modes and their associated "tiny" values. As long as you have a small number of variations, there is no need to report the entire thing verbatim. A single byte can carry a lot of information, as long as the context of this byte is understood.

my (@possible_values) = qw(view edit modify delete nuke);
my (%possible_values) = do { my $n; map { $_, $n++ } @possible_values;
+ };

$encoded_param = $possible_values{'mode'};

$decoded_param = $possible_values[$encoded_param];
[download]

Numbers, likewise, can be squished into "packed binary" which can reduce 10-digit numbers into 4-byte values, or about 6-bytes after Base64, which is a moderate but valuable decrease.

Here's a compactor that I just sketched out. Use for entertainment purposes only, as it is untested. It takes in a SCALAR and returns a squished up version with a type identification byte which can be used to desquish it properly later.

sub Squish
{
        my ($what) = @_;

        if ($what =~ /^\-?[0-9]+$/)
        {
                if ($what >= 0)
                {
                        if ($what <= 255)
                        {
                                return pack ("CC", 0x01, $what);
                        }
                        elsif ($what <= 65535)
                        {
                                return pack ("CS", 0x02, $what);
                        }
                        elsif ($what <= 4294967295)
                        {
                                return pack ("CL", 0x04, $what);
                        }
                }
                elsif ($what >= -128 && $what <= 127)
                {
                        return pack ("Cc", 0x09, $what);
                }
                elsif ($what >= -32768 && $what <= 32767)
                {
                        return pack ("Cs", 0x0A, $what);
                }
                elsif ($what >= 2147483648 && $what <= 2147483647)
                {
                        return pack ("Cl", 0x0B, $what);
                }
        }
        elsif ($what =~ /^\-?[0-9]+(?:\.[0-9]+)?(?:e[\+\-]\d+)?$/)
        {
                return pack ("Cd", 0x0C, $what);
        }
        elsif (length ($what) < 16)
        {
                return pack ("C", 0x0C & (length($what) << 4)).$what;
        }
        elsif (length ($what) <= 255)
        {
                return pack ("CC", 0x0D, length($what)).$what;
        }

        return pack ("CS", 0x0E, length($what)).$what;
}
[download]