Why you so slow JS???

indigo.js

var Interval = function(lower, upper) {
    this.lower = lower;
    this.upper = upper;
}

function interval_add(a, b) {
    return new Interval(a.lower + b.lower, a.upper + b.upper);
}

function interval_sub(a, b) {
    return new Interval(a.lower - b.lower, a.upper - b.upper);
}

function interval_mul(a, b) {
    var lower = Math.min(a.lower * b.lower, a.lower * b.upper, a.upper * b.upper);
    var upper = Math.max(a.lower * b.lower, a.lower * b.upper, a.upper * b.upper);
    return new Interval(lower, upper);
}

var intervals = new Array();

function indigo(constraints, variables) {
    for(var i = 0; i < 20; i++) {
        intervals[i] = new Interval(Math.random(), Math.random());
    }

    var iv = new Interval(0,0);

    for(var i = 0; i < 1e7; i++) {
        for(var j = 0; j < 19; j++) {
            iv = interval_add(iv, interval_mul(intervals[j], intervals[j + 1]));
        }
    }

    console.log(iv.lower, iv.upper);
}

indigo()

indigo.lua

local max = math.max
local min = math.min

local interval_mt
local interval_new

interval_mt = {
    __index = interval_mt;
    __add = function(a, b)
        return interval_new(a.lower + b.lower, a.upper + b.upper)
    end;

    __sub = function(a, b)
        return interval_new(a.lower - b.lower, a.upper - b.upper)
    end;

    __mul = function(a, b)
        local lower = min(a.lower * b.lower, a.lower * b.upper, a.upper * b.upper)
        local upper = max(a.lower * b.lower, a.lower * b.upper, a.upper * b.upper)
        return interval_new(lower, upper)
    end;

    __div = function(a, b)
        reciprocal = interval_new(1 / b.upper, 1 / a.upper)
        return a * reciprocal
    end;
}

interval_new = function(lower, upper)
    return setmetatable({upper = upper; lower = lower}, interval_mt)
end

local intervals = {}

local function indigo(constraints, variables)

    for i = 1, 20 do
        intervals[i] = interval_new(math.random(), math.random())
    end

    local iv = interval_new(0,0)
    for ii = 1, 1e7 do
        for i = 1, 19 do
            iv = iv + intervals[i] * intervals[i + 1]
        end
    end

    print(iv.lower, iv.upper)
end

indigo()

results

[josh@archprime ~]$ perf stat -r 5 node indigo.js 
18821829.261309687 78935338.29054944
21653322.733843245 73055958.5489864
17679419.27493577 64168128.62364557
7719459.937230684 86016052.58084385
11796860.698572649 46822903.31803182

 Performance counter stats for 'node indigo.js' (5 runs):

      19157.580691 task-clock                #    1.002 CPUs utilized            ( +-  0.36% )
            22,720 context-switches          #    0.001 M/sec                    ( +-  2.22% )
                38 cpu-migrations            #    0.002 K/sec                    ( +- 17.55% )
             3,461 page-faults               #    0.181 K/sec                    ( +-  0.01% )
    69,308,982,775 cycles                    #    3.618 GHz                      ( +-  0.30% ) [83.33%]
     9,341,780,073 stalled-cycles-frontend   #   13.48% frontend cycles idle     ( +-  1.48% ) [83.28%]
     5,584,916,732 stalled-cycles-backend    #    8.06% backend  cycles idle     ( +-  1.69% ) [66.70%]
   162,788,891,026 instructions              #    2.35  insns per cycle        
                                             #    0.06  stalled cycles per insn  ( +-  0.07% ) [83.33%]
    44,059,476,773 branches                  # 2299.846 M/sec                    ( +-  0.16% ) [83.31%]
       147,080,377 branch-misses             #    0.33% of all branches          ( +-  2.19% ) [83.38%]

      19.109933486 seconds time elapsed                                          ( +-  0.40% )

[josh@archprime ~]$ perf stat -r 5 luajit indigo.lua 
18545291.446756	81362168.189728
18545291.446756	81362168.189728
18545291.446756	81362168.189728
18545291.446756	81362168.189728
18545291.446756	81362168.189728

 Performance counter stats for 'luajit indigo.lua' (5 runs):

       3018.966034 task-clock                #    0.996 CPUs utilized            ( +-  0.17% )
               310 context-switches          #    0.103 K/sec                    ( +-  0.13% )
                 4 cpu-migrations            #    0.001 K/sec                    ( +- 51.67% )
               331 page-faults               #    0.110 K/sec                    ( +-  0.06% )
    11,127,199,502 cycles                    #    3.686 GHz                      ( +-  0.08% ) [83.28%]
     2,745,288,236 stalled-cycles-frontend   #   24.67% frontend cycles idle     ( +-  0.30% ) [83.30%]
     1,226,851,059 stalled-cycles-backend    #   11.03% backend  cycles idle     ( +-  0.15% ) [66.69%]
    25,684,644,759 instructions              #    2.31  insns per cycle        
                                             #    0.11  stalled cycles per insn  ( +-  0.03% ) [83.37%]
     6,823,459,833 branches                  # 2260.198 M/sec                    ( +-  0.01% ) [83.38%]
         5,885,114 branch-misses             #    0.09% of all branches          ( +-  0.18% ) [83.35%]

       3.030054202 seconds time elapsed                                          ( +-  0.16% )