Slower than Ruby 1.9, Rubinius for select String#unpack results

~/projects/rubinius ➔ jruby --server -I benchmark/lib/ benchmark/core/string/bench_unpack.rb 
    string unpack @*  2954261.4 (±12.1%) i/s -   14252964 in   4.950668s (cycle=22732)
    string unpack A*  1874260.4 (±13.7%) i/s -    9116352 in   4.993779s (cycle=29988)
    string unpack B*  1845823.7 (±2.5%) i/s -    9190970 in   4.982551s (cycle=22417)
    string unpack b*  1760285.5 (±7.5%) i/s -    8743950 in   5.006990s (cycle=38862)
    string unpack C*  1219630.7 (±23.5%) i/s -    5658219 in   5.009728s (cycle=34713)
    string unpack c*  1691418.7 (±10.6%) i/s -    8323263 in   4.987737s (cycle=27837)
    string unpack E*  2377683.4 (±13.4%) i/s -   11602525 in   4.992931s (cycle=34025)
    string unpack e*  2128774.6 (±17.7%) i/s -   10162296 in   4.999965s (cycle=36424)
    string unpack F*  2261388.3 (±11.4%) i/s -   11106072 in   4.989234s (cycle=34278)
    string unpack f*  2056478.3 (±15.4%) i/s -    9944730 in   4.998399s (cycle=35265)
    string unpack G*  2247222.2 (±18.8%) i/s -   10357480 in   5.079501s (cycle=36470)
    string unpack g*  1844503.2 (±18.7%) i/s -    8723274 in   4.988684s (cycle=29671)
    string unpack H*  2213835.1 (±9.5%) i/s -   10927780 in   4.997926s (cycle=32915)
    string unpack h*  1946836.4 (±12.0%) i/s -    9511776 in   4.992093s (cycle=29088)
    string unpack I*  2038903.5 (±24.6%) i/s -    9280040 in   5.080328s (cycle=36680)
    string unpack i*  2504587.8 (±3.4%) i/s -   12470556 in   4.985348s (cycle=33523)
    string unpack L*  2230028.7 (±17.3%) i/s -   10643895 in   4.999535s (cycle=36081)
    string unpack l*  2009144.3 (±19.4%) i/s -    9509790 in   4.990518s (cycle=35886)
    string unpack M*  1555514.6 (±8.3%) i/s -    7719292 in   5.010518s (cycle=32434)
    string unpack m*  1842944.8 (±27.2%) i/s -    8170800 in   5.008332s (cycle=34045)
    string unpack N*  1900883.3 (±17.9%) i/s -    9073032 in   4.987707s (cycle=29944)
    string unpack n*  2039130.8 (±14.2%) i/s -    9896030 in   4.992591s (cycle=32446)
    string unpack Q*   828886.7 (±1.9%) i/s -    4140236 in   4.996691s (cycle=23932)
    string unpack q*  2001000.9 (±18.1%) i/s -    9243612 in   4.996399s (cycle=36681)
    string unpack S*  1770961.0 (±2.2%) i/s -    8838912 in   4.993620s (cycle=32496)
    string unpack s*  1753344.2 (±17.0%) i/s -    8422250 in   5.004650s (cycle=33689)
    string unpack U*  1661570.8 (±2.8%) i/s -    8298381 in   4.998487s (cycle=30397)
    string unpack V*  2316742.8 (±27.5%) i/s -    9953301 in   4.999669s (cycle=35421)
    string unpack v*  1764401.8 (±2.7%) i/s -    8802189 in   4.992633s (cycle=32967)
    string unpack w*   463732.2 (±1.1%) i/s -    2334562 in   5.034858s (cycle=21418)
    string unpack Z*  2157403.5 (±5.5%) i/s -   10733646 in   5.002923s (cycle=36509)

~/projects/rubinius ➔ ruby1.9 -I benchmark/lib/ benchmark/core/string/bench_unpack.rb 
    string unpack @*  1965810.0 (±7.9%) i/s -    9786985 in   5.015848s (cycle=44285)
    string unpack A*  1392224.6 (±5.4%) i/s -    6958086 in   5.012022s (cycle=39989)
    string unpack B*   912818.3 (±3.5%) i/s -    4562184 in   5.004101s (cycle=34562)
    string unpack b*   851300.2 (±15.6%) i/s -    4089840 in   5.062876s (cycle=34082)
    string unpack C*   952789.3 (±6.8%) i/s -    4765320 in   5.026512s (cycle=34038)
    string unpack c*   954255.1 (±7.6%) i/s -    4779984 in   5.038315s (cycle=36212)
    string unpack E*  1439471.8 (±4.2%) i/s -    7222152 in   5.026613s (cycle=42989)
    string unpack e*  1120600.5 (±5.4%) i/s -    5609685 in   5.020971s (cycle=39785)
    string unpack F*  1121132.9 (±5.2%) i/s -    5603815 in   5.012590s (cycle=38647)
    string unpack f*  1117793.7 (±4.9%) i/s -    5613120 in   5.033978s (cycle=38980)
    string unpack G*  1432808.2 (±3.9%) i/s -    7189260 in   5.025676s (cycle=42540)
    string unpack g*  1049162.0 (±4.7%) i/s -    5241894 in   5.007863s (cycle=38262)
    string unpack H*  1232890.8 (±19.2%) i/s -    5517720 in   5.006530s (cycle=40872)
    string unpack h*  1338014.3 (±7.1%) i/s -    6663186 in   5.014254s (cycle=38966)
    string unpack I*  1825338.4 (±6.3%) i/s -    9086004 in   4.998433s (cycle=45204)
    string unpack i*  1832283.0 (±5.9%) i/s -    9128445 in   5.000295s (cycle=44529)
    string unpack L*  1775121.3 (±11.2%) i/s -    8677056 in   5.001303s (cycle=45193)
    string unpack l*  1832273.4 (±5.6%) i/s -    9136718 in   5.002833s (cycle=44353)
    string unpack M*  1319573.4 (±3.9%) i/s -    6606522 in   5.013780s (cycle=40781)
    string unpack m*  1025278.3 (±6.9%) i/s -    5091264 in   5.000878s (cycle=35356)
    string unpack N*  1769005.4 (±12.6%) i/s -    8672770 in   5.096087s (cycle=44705)
    string unpack n*  1033523.5 (±7.4%) i/s -    5168256 in   5.023747s (cycle=30048)
    string unpack Q*  1388404.5 (±3.9%) i/s -    6946238 in   5.010584s (cycle=41102)
    string unpack q*  1810819.8 (±6.9%) i/s -    9043136 in   5.019791s (cycle=44768)
    string unpack S*  1033950.6 (±8.1%) i/s -    5159820 in   5.022367s (cycle=37390)
    string unpack s*  1034262.0 (±8.2%) i/s -    5152754 in   5.016546s (cycle=36287)
    string unpack U*   974896.2 (±9.5%) i/s -    4834278 in   5.009431s (cycle=35031)
    string unpack V*  1827094.5 (±5.6%) i/s -    9124770 in   5.010848s (cycle=44295)
    string unpack v*  1039977.0 (±8.2%) i/s -    5179860 in   5.014029s (cycle=36999)
    string unpack w*   377163.6 (±4.6%) i/s -    1900506 in   5.049947s (cycle=21354)
    string unpack Z*  1380516.9 (±5.1%) i/s -    6889932 in   5.003162s (cycle=40292)

~/projects/rubinius ➔ bin/rbx -I benchmark/lib/ benchmark/core/string/bench_unpack.rb 
    string unpack @*  2606154.3 (±0.9%) i/s -   12989863 in   4.984703s (cycle=35983)
    string unpack A*  1884009.6 (±3.0%) i/s -    9406130 in   4.997398s (cycle=28078)
    string unpack B*  1475351.9 (±3.8%) i/s -    7359744 in   4.997298s (cycle=33152)
    string unpack b*  1414095.0 (±4.4%) i/s -    7039951 in   4.993577s (cycle=31013)
    string unpack C*  1376045.9 (±1.3%) i/s -    6877073 in   4.998581s (cycle=34909)
    string unpack c*  1340153.2 (±4.3%) i/s -    6662700 in   4.986458s (cycle=33650)
    string unpack E*  2188220.1 (±2.8%) i/s -   10923981 in   4.996529s (cycle=35583)
    string unpack e*  1804429.4 (±3.5%) i/s -    8990888 in   4.989446s (cycle=34984)
    string unpack F*  1874232.8 (±9.7%) i/s -    9235350 in   4.993745s (cycle=34205)
    string unpack f*  1949979.8 (±3.7%) i/s -    9719332 in   4.991900s (cycle=34223)
    string unpack G*  2127909.9 (±3.8%) i/s -   10593649 in   4.986403s (cycle=34507)
    string unpack g*  1569167.4 (±16.6%) i/s -    7259253 in   4.988924s (cycle=34081)
    string unpack H*  1543582.0 (±4.6%) i/s -    7689066 in   4.994166s (cycle=32307)
    string unpack h*  1736990.5 (±2.0%) i/s -    8664832 in   4.990672s (cycle=31856)
    string unpack I*  2226063.0 (±0.9%) i/s -   11119191 in   4.995431s (cycle=36697)
    string unpack i*  2212025.1 (±0.9%) i/s -   11063387 in   5.001842s (cycle=37759)
    string unpack L*  2190515.0 (±0.8%) i/s -   10945269 in   4.997023s (cycle=36123)
    string unpack l*  2181140.0 (±1.0%) i/s -   10907819 in   5.001458s (cycle=36481)
    string unpack M*  1699922.9 (±1.1%) i/s -    8494040 in   4.997344s (cycle=32420)
    string unpack m*  1857496.3 (±1.8%) i/s -    9283680 in   4.999748s (cycle=32235)
    string unpack N*  2209939.9 (±1.2%) i/s -   11034288 in   4.993775s (cycle=37278)
    string unpack n*  1809322.8 (±2.4%) i/s -    9038380 in   4.998682s (cycle=34763)
    string unpack Q*   617391.6 (±10.0%) i/s -    3045870 in   4.988910s (cycle=22562)
    string unpack q*  2220877.7 (±0.9%) i/s -   11083072 in   4.990770s (cycle=35984)
    string unpack S*  1719627.8 (±13.3%) i/s -    8124536 in   5.047334s (cycle=34426)
    string unpack s*  1797249.1 (±2.1%) i/s -    8977360 in   4.997419s (cycle=32062)
    string unpack U*  1565410.2 (±1.9%) i/s -    7829556 in   5.003418s (cycle=31444)
    string unpack V*  2197583.4 (±0.9%) i/s -   10959652 in   4.987553s (cycle=33011)
    string unpack v*  1716471.7 (±1.6%) i/s -    8562390 in   4.989719s (cycle=33578)
    string unpack w*   417229.3 (±1.6%) i/s -    2083024 in   4.993914s (cycle=20624)
    string unpack Z*  1955882.3 (±2.4%) i/s -    9771994 in   4.999457s (cycle=31121)