title: why is dot product in dask slower than in numpy
body: <p>a dot product in dask seems to run much slower than in numpy:</p>
  
  <pre><code>import numpy as np
  x_np = np.random.normal(10, 0.1, size=(1000,100))
  y_np = x_np.transpose()
  %timeit x_np.dot(y_np)
  # 100 loops, best of 3: 7.17 ms per loop
  
  import dask.array as da
  x_dask = da.random.normal(10, 0.1, size=(1000,100), chunks=(5,5))
  y_dask = x_dask.transpose()
  %timeit x_dask.dot(y_dask)
  # 1 loops, best of 3: 6.56 s per loop
  </code></pre>
  
  <p>Does anybody know what might be the reason for that? Is there anything I'm missing here?</p>