benchmarking lua elsif vs hashtable

elseif_lookup_sequential.lua

local nBranch = 1
local nLoops = 2000000

print("NUMBER_BRANCHS,TIME_ELSEIF,TIME_LOOKUP")
while (nBranch <= 100) do
	io.write(nBranch)
	io.write(",")
	local valueName = "iInner"
	local elseifCodeTable = {"local iOutter = 1\nwhile iOutter <= " .. nLoops .. " do\n\tlocal iInner = 1\n\tlocal dummy;\n\twhile iInner <= " .. nBranch .. " do\n", "\t\tend\n\t\tiInner = iInner + 1\n\tend\n\tiOutter = iOutter + 1\nend"}
	local i = 1

	while (i <= nBranch) do
		if i ~= 1 then
			table.insert(elseifCodeTable, #elseifCodeTable, string.format("\t\telseif %s == %i then\n\t\t\t dummy = true\n", valueName, i))
		else
			table.insert(elseifCodeTable, #elseifCodeTable, string.format("\t\tif %s == 1 then\n\t\t\t dummy = true\n", valueName))
		end

		i = i + 1
	end


	local elseifFunction, err = loadstring(table.concat(elseifCodeTable))


	if not elseifFunction then error(err) end

	local time = os.clock()
	elseifFunction()
	io.write(os.clock() - time)
	io.write(",")
	local lookupTable = {}
	i = 1

	while (i <= nBranch) do
		lookupTable[i] = true
		i = i + 1
	end
	local function lookUpFunction()
		local iOutter = 1

		while (iOutter <= nLoops) do
			local iInner = 1

			while iInner <= nBranch do
				local dummy = lookupTable[iInner]
				iInner = iInner + 1
			end

			iOutter = iOutter + 1
		end
	end

	time = os.clock()
	lookUpFunction()
	io.write(os.clock() - time)
	io.write("\n")
	nBranch = nBranch + 1
end

Here are the results using PUC-lua:

NUMBER_BRANCHS,TIME_ELSEIF,TIME_LOOKUP
1,0.107,0.096
2,0.16,0.14
3,0.272,0.23
4,0.343,0.243
5,0.433,0.319
6,0.617,0.344
7,0.748,0.337
8,0.912,0.404
9,1.123,0.475
10,1.35,0.554
11,1.458,0.561
12,1.819,0.59
13,2.023,0.597
14,2.323,0.702
15,2.546,0.751
16,2.96,0.73
17,3.309,0.837
18,3.606,0.918
19,3.829,0.893
20,4.214,0.884
21,4.734,1.056
22,5.139,1.295
23,5.715,1.052
24,5.769,1.167
25,6.157,1.165
26,6.688,1.21
27,7.048,1.171
28,7.506,1.337
29,8.029,1.454
30,9.1,1.288
31,9.157,1.401
32,9.61,1.411
33,10.272,1.436
34,10.768,1.475
35,11.318,1.621
36,11.948,1.644
37,12.471,1.669
38,13.006,1.656
39,13.518,1.691
40,14.265,1.775
41,14.963,1.846
42,15.878,1.828
43,16.24,1.988
44,17.126,1.876
45,17.732,2.043
46,18.589,2.06
47,19.688,2.277
48,20.391,2.115
49,20.81,2.229
50,21.505,2.263
51,22.774,2.271
52,23.103,2.303
53,24.292,2.285
54,25.066,2.442
55,25.998,2.2950000000001
56,26.769,2.453
57,27.636,2.474
58,28.91,2.545
59,29.99,2.635
60,30.652,2.83
61,31.969,2.748
62,32.769,2.8270000000001
63,33.738,2.7729999999999
64,34.488,2.6959999999999
65,35.821,2.819
66,37.433,3.087
67,37.632,2.9
68,39.145,3.0349999999999
69,40.069,3.1689999999999
70,40.911,3.0469999999998
71,41.686,3.8920000000001
72,44.316,3.248
73,44.544,3.0900000000001
74,45.353,3.1219999999998
75,46.339,3.307
76,47.682,3.191
77,48.361,3.3059999999998
78,50.24,3.336
79,51.759,3.4960000000001
80,52.909,3.4159999999999
81,54.311,3.729
82,56.206,3.6880000000001
83,57.17,3.585
84,58.137,3.855
85,59.874,3.7270000000001
86,61.221,3.8860000000002
87,62.229,3.7040000000002
88,63.234,3.9470000000001
89,65.761,3.9430000000002
90,69.189,4.1620000000003
91,69.851,4.0529999999999
92,69.675,4.636
93,71.732,4.136
94,72.308,4.1330000000003
95,73.739,4.239
96,75.403,4.1599999999999
97,78.109,4.3800000000001
98,78.06,4.1770000000001
99,78.434,4.5119999999997
100,81.095,4.3359999999998

PUC_Lua Graph