Too long for a comment:

Packing the data, as @0x4A4D suggests, seems to "fix" the problem, except in InterpolationOrder -&gt; 0.  See What is a Mathematica packed array? for an explanation of the importance of packed arrays.

TableForm[
 ParallelTable[
  Benchmark[data, n],
  {data,  Developer`ToPackedArray /@ N@{testdata, testdataPoints, testdataPoints2}},
  {n, 0, 2}], 
 TableHeadings -&gt; {{"Array", "Integer", "Float"}, {0, 1, 2}}]




This way is faster:

TableForm[
 Table[
  Timing[
   ifn = Interpolation[data, InterpolationOrder -&gt; n]; 
   DensityPlot[ifn[i, j],
    {i, -1, 1}, {j, -1, 1}, PlotPoints -&gt; 101, 
    ColorFunction -&gt; "Rainbow", PlotRange -&gt; Full]],
  {data, {testdataPoints2}}, {n, 0, 2}], 
 TableHeadings -&gt; {{"Float"}, {0, 1, 2}}]




ListDensityPlot performance when scaling axes
total newbie trying to work through the rails tutorial on lynda.com

The code is really short and exactly the way it is on the video, yet I can't get my page to render the partial. When I pull run it on the server it does not render the partial at all, but just skips it. No error messages. Thanks in advance

this is edit.html.erb

&lt;%= link_to("&lt;&lt; Back to List", {:action =&gt; 'list'}, :class =&gt; 'back=link')%&gt;

&lt;div class="subject edit"&gt;
    &lt;h2&gt;Edit Subject&lt;/h2&gt;

    &lt;%= form_for(:subject, :url =&gt; {:action =&gt; 'update', :id=&gt;@subject.id}) do |f| %&gt;

        &lt;% render :partial =&gt; 'form', :locals =&gt; {:f =&gt; f} %&gt;

        &lt;div class="form-buttons"&gt;
            &lt;%= submit_tag("Update Subject")%&gt;
        &lt;/div&gt;

    &lt;% end %&gt;
&lt;/div&gt;


and this is _form.html.erb

&lt;table summary="Subject form fields"&gt;
    &lt;tr&gt;
        &lt;th&gt;Name&lt;/th&gt;
        &lt;td&gt;&lt;%= f.text_field(:name) %&gt;&lt;/td&gt;
    &lt;/tr&gt;
    &lt;tr&gt;
        &lt;th&gt;Position&lt;/th&gt;
        &lt;td&gt;&lt;%= f.text_field(:position) %&gt;&lt;/td&gt;
    &lt;/tr&gt;
    &lt;tr&gt;
        &lt;th&gt;Visible&lt;/th&gt;
        &lt;td&gt;&lt;%= f.text_field(:visible) %&gt;&lt;/td&gt;
    &lt;/tr&gt;
&lt;/table&gt;

