Improve performance

```

deadhorse in ~/git/byte on improve-performance λ node -v
v0.10.28

deadhorse in ~/git/byte on improve-performance λ node benchmark.js 
put()       x 17,447,349 ops/sec ±2.86% (82 runs sampled)
putChar()   x 34,406,515 ops/sec ±2.70% (81 runs sampled)
putShort()  x 18,413,649 ops/sec ±2.56% (84 runs sampled)
putInt()    x 16,135,472 ops/sec ±2.40% (84 runs sampled)
putFloat()  x 7,902,405 ops/sec ±2.75% (83 runs sampled)
putDouble() x 7,640,646 ops/sec ±2.69% (85 runs sampled)
putLong()   x 14,107,238 ops/sec ±2.09% (89 runs sampled)
putBILong() x 1,937,607 ops/sec ±4.64% (84 runs sampled)
putBSLong() x 576,982 ops/sec ±5.20% (81 runs sampled)
putString() x 628,374 ops/sec ±7.02% (81 runs sampled)
putRawStr() x 768,525 ops/sec ±2.98% (88 runs sampled)
get()       x 1,911,615 ops/sec ±3.04% (89 runs sampled)
getChar()   x 31,305,863 ops/sec ±2.82% (81 runs sampled)
getShort()  x 17,987,782 ops/sec ±2.98% (81 runs sampled)
getInt()    x 14,352,414 ops/sec ±4.79% (79 runs sampled)
getFloat()  x 6,786,484 ops/sec ±3.63% (84 runs sampled)
getDouble() x 6,617,909 ops/sec ±5.54% (81 runs sampled)
getLong()   x 8,459,498 ops/sec ±2.70% (88 runs sampled)
getString() x 999,392 ops/sec ±4.30% (84 runs sampled)
getRawStr() x 966,941 ops/sec ±5.20% (76 runs sampled)
```

long, string still too slow.