Slow to start blenderplayer after upgrading

I upgrade my system from Ubuntu 14.04 to Ubuntu 16.04 and blender from 2.69 to 2.76.
For the same .blend file, now it takes about ten minutes to start up. I used to be 20 seconds.
Anyone has any ideas?

make sure “Use Material Caches” is enabled in the render panel.

“Use Material Caches” is not enabled in the old version either.
I tried to enable it in new version. Still slow…