Before reviewing these tips, first consider if you really need to do a render.
Is a render going to provide more information than a shaded view?
It takes a lot of time and skill to create a photo-realistic image, much more than just hitting the render button.
1. Watch the View Size / Printer DPI Size
Because the Width / Height of the rendering for the “Printer” Resolutions are linked to the Crop Region size of the view, make sure to verify this setting.
A large crop region combined with a high DPI will add to the rendering time, i.e. the more pixels rendered the longer it takes.
If possible reduce the crop region size or lower the DPI to 75 or 150 DPI.
2. Limit the number of lights you are rendering
Lights are one of the largest contributors to rendering times.
You can selectively turn off artificial lights not necessary for the view, groups of lights, or use the section box approach in #3 below.
If the appearance of light fittings is not important in your render consider using fewer more powerful lights (edit light fitting settings to increase their luminosity).
3. Use a Section Box (but not Far Clip Offset)
By enabling a section box in the view and cropping unnecessary geometry you can greatly reduce the rendering times.
Because section boxes also work for linked files, daylight portals and lights this is a great approach to cut down rendering times.
Not that view parameter Far Clip Offset, which excludes objects beyond the clip normally, does not do so when rendering. Use a section box instead.
4. Keep custom material maps to a reasonable size
Avoid using very large dimensional image files, or large file-size images for the Material > Render Appearance > Image .
As a reference you can open some of the included maps in a folder such as:
C:\Program Files\Common Files\Autodesk Shared\Materials2011\assetlibrary_base.fbm\3\Mats
5. Render a Region
Render a region of the view to limit the geometry which will be rendered.
Keep in mind this does not limit the light[s] calculation outside the region for rendering as a section box would.
For example, an artificial light outside the region will still be calculated and show up on the rendering dialog artificial light count.
But be aware turning lights off to make a region render quicker will mean the reuslt is not a true representation of a full render with those lights on.
6. Linked Files
If you don’t need geometry in a linked file temporarily unload the link prior to rendering.
Because geometry and lights are calculated and will render from a link even if it is not visible in the immediate view this can greatly extend the rendering time.
7. Avoid adjusting the Render Quality Settings higher than necessary
Keep in mind even the included “Best” render quality setting limits the values to the following:
Image Precision (Antialiasing): 8 out of 10
Maximum Number of Reflections: 4 out of 100
Maximum Number of Refractions: 8 out of 100
Blurred Reflections Precision: 7 out of 11
Blurred Refractions Precision: 5 out of 11
Soft Shadows: Enabled
Soft Shadow Precision: 6 out of 10
Compute Indirect and Sky Illumination: Enabled
Indirect Illumination Precision: 7 out of 10
Indirect Illumination Smoothness: 8 out of 10
Indirect Illumination Bounces: 2 out of 5
Daylight Portal Options: Not Enabled
Setting these higher than the “Best” setting, can substantially add to the rendering process time.
8. Daylight Portals
If the current view you are rendering does not need to utilize daylight portals for windows, doors and curtain walls they can be disabled.
For example, if the view does not include a window illuminated from exterior daylight you could un-check this option.
9. Render on a workstation with a multi-core processor
Revit 2011 products do not limit the number of processor cores for the rendering process.