It is possible, but using a while loop is better:

my $raw = "foo=1 baR= red BOO = 5.6 Baz =3";
my %params = ();

use Benchmark qw/cmpthese/;

my $test = {
    'map' => sub {
        %params =
          map { (lc($_) => $raw =~ /$_\s*=\s*(\S+)/ ) }
          $raw =~ /(\S+)\s*=/g;
        %params = ();
    },
    'while' => sub {

        $params{lc($1)} = $2 while
              $raw =~ /(\S+)\s*=\s*(\S+)/g;
        %params = ();
    }
};

#no regexp initialisation in benchmark
$_->() for values %$test;

cmpthese( -4 , $test );
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