Big charge of cpu

Hi,

I'm using your library (run_model.lua) that I modified for computing a 2fps stream of images buffered in memory with the default configurations:

```
-image_size, 480
-rpn_nms_thresh, 0.7
-final_nms_thresh, 0.3
-num_proposals, 1000
-gpu, 1
-use_cudnn, 1
```

But I get a big charge of cpu in one core (100% cpu usage). I also have seen that this is produced by model:forward_test(img_caffe:type(dtype))

Is it normal that cpu usage?

Luarocks packages:

```
argcheck scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

csvigo scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

cudnn scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

cunn scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

cunnx scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

cutorch scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

cv scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

cwrap scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

dok scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

dpnn scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

env scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

fftw3 scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

fn 0-0 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

gnuplot scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

graph scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

graphicsmagick 1.scm-0 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

hdf5 20-0 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

image 1.1.alpha-0 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

loadcaffe 1.0-0 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

logroll 0-0 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

lua-cjson 2.1.0-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

luaffi scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

luafilesystem 1.6.3-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

luasocket 3.0rc1-2 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

moses 1.4.0-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

nn scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

nngraph scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

nnx 0.1-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

optim 1.0.5-0 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

paths scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

penlight scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

pprint 0-0 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

qtlua scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

qttorch scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

signal scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

stnbhwd scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

struct 1.4-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

sundown scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

sys 1.1-0 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

threads scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

torch scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

torch-rnn scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

totem 0-0 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

trepl scm-1 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

util 0-0 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks

xlua 1.0-0 (installed) - /home/karpathy-dev/torch/install/lib/luarocks/rocks
```

Cuda version:

```
nvcc: NVIDIA (R) Cuda compiler driver
Copyright (c) 2005-2016 NVIDIA Corporation
Built on Wed_May__4_21:01:56_CDT_2016
Cuda compilation tools, release 8.0, V8.0.26
```

CPU info:

```
Placa: Z97X-Gaming 3
CPU: Intel(R) Core(TM) i5-4690K CPU @ 3.50GHz
RAM (16GB): G. Skill F3-1600C9S-8GXM (2x8GB) In same channel
GPU: NVidia GTX1080 Founders Edition x2 in SLI
HD: Seagate Desktop HDD ST2000DM001 2TB 64MB Cache SATA 6.0Gb/s 3.5"
Fuente: NOX Hummer 850W Bronze+
```