As the topic. How to speed up houdini? I run houdini with my laptop on a linux_x64 system. Its no problem to do a normal job. It react qucikly. But when I dealing with relatively larger scene(such as Natural History scene from 3drender.com) it cook very slow when i change something.
And its not speed up when i put houdini on a quadcore machine. I even turned on the “muti core cooking” from environment setting. It still using single core cooking geometry.
can anyone help me with this?

The first thing I would do is open the Performance Monitor and check to see what specifically is slowing things down.

I think most SOPs are still single-threaded and will be so until H12 is out. What you can do is cache as much as possible and use instances wherever you can.

If you use the Copy SOP largely around the scene, as the number of copies surpass the 100s you'll experience slowness, specially if your copies have lots of expressions and stamped variables. The only way around it that I can think is to try and implement LOD in your copied elements and use an expression to automatically switch the detail in render time. That way you'll have a waorkable scene in the viewport and as much detail as you need in render.

Also, wherever you can, use VOPs! They are multi-threaded and should take advantage of your machine's power.

Houdini is awesome, but you still need to be smart about optimization cause the machines we have will never be as fast as we wish!

A couple of other things to consider.
You can use the Tristrip sop on heavier geometry to improve their efficiency.

As well, you can use the Display/Render flags on sops to advantage, in that you can display simpler geometry but render the complex/finished models.

You objective is to reduce the complexity of geometry for the display, thus speeding up your interaction, yet keep the complex geometry for rendering.