This is the sort of code where I would expect to be faster in C. Lots of numerical comparisons, and not much else. However, there are a couple of things that jump out at me. One is your mvsrt() routine. I think you could remove that entirely by changing this line:

my $tv = mvsrt($cv, $oper, $amt);
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to this:

my $tv = ( ($cv <=> $amt) == ($oper - 1) );
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(Well, that changes the actual operation each value of $oper performs, but you get the idea.)

Also, you have lots of C-style for loops which could be rewritten to use foreach. For example, change this:

       my $absMax = 0;
        for(my $i = $params[1] - 5; $i < $params[1]; $i++){
            if($rddt[$i] > $absMax){
                $absMax = $rddt[$i];
            }
        }              
        $returnValue = $rddt[$params[1]] - $absMax;
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to this:

       my $absMax = 0;
        # loop over array slice
        foreach my $rddt_value (@rddt[($params[1] - 5) .. $params[1]])
+{
            if($rddt_value > $absMax){
                $absMax = $rddt_value;
            }
        }              
        $returnValue = $rddt[$params[1]] - $absMax;
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Foreach loops do tend to run quite a bit faster, and you have many of these.