ASP.NET MVC - performance issue when using EditorFor

Question

I have an MVC3 page that renders a view containing a table. The table has a column for each day of the month, and there are 7 rows, each representing a department of an organisation.

In each cell of the table, there is an input textbox, where the user must enter a numeric value representing energy usage.

The class model looks like this:

public class EnergySheet
{
    public DateTime Month { get; set; }
    public List<DepartmentValue> DepartmentValues { get; set; }
}

public class DepartmentValue
{
    public int DepartmentId { get; set; }
    public string DepartmentName { get; set; }
    public List<DayValue> DayValues { get; set; }
}

public class DayValue
{
    public DateTime Date { get; set; }
    public decimal EnergyUsage { get; set; }
}

And the views are rendered like this:

EnergySheet.cshtml:

@model EnergySheet

@using(Html.BeginForm()){
    <table>
        <tbody>
            @Html.EditorFor(x => x.DepartmentValues)
        </tbody>
    </table>
    <input type="submit" value="Save" />
}

DepartmentValue.cshtml:

@model DepartmentValue
<tr>
    @Html.EditorFor(x => x.DayValue)
</tr>

DayValue.cshtml

@model DayValue
<td>
    @Html.EditorFor(x => x.EnergyUsage)
</td>

The problem

This all renders fine, and the model binds correctly when posted back to the server. However, the problem is performance - the page takes 10-15 seconds to render for a grid containing around 200 input fields.

I've ensured that I'm running in release mode, and the Web.config has <compilation debug="false"> - so it shouldn't be a problem with view paths not being cached. I'm using a powerful enough machine - quad i7, 16GB, etc.

Attempted fix

I tried replacing the "automatic iteration" over the editor templates by explicitly specifying the view template names - ie, @Html.EditorFor(x => x.DepartmentValues) becomes @Html.EditorFor(x => x.DepartmentValues, "DepartmentValues") and @Html.EditorFor(x => x.DayValue) becomes @Html.EditorFor(x => x.DayValue, "DayValue"). This also means manually iterating over the collections within the templates - as explained in this post. This solves the performance problem - the page renders instantly - but all the automatic model binding is lost.

My question is - should the automatic rendering of editor templates really be this slow? Or am I doing something wrong? A page with just 200 input fields surely shouldn't tax the rendering engine this much?