I installed Magento 2.0.4 (composer) on Windows 10. Pages take up to 10 seconds or more to load. I tried several solutions published here to speed up the loading process on WAMP environments but none of them worked.
Then I set up an Ubuntu virtual machine (on Windows 10 host) to check whether the issue was caused by Windows. I installed Magento 2.0.4 again on this virtual machine and the result is the same: 10 seconds to load pages.
Windows - when loading a page the Apache process uses up to 50% CPU. I noticed that two apache process are running. However only one seems active (50%) when the page loads, the other one is at 0%.
Ubuntu - when loading a page the only 2 process showing activity are firefox 5% and gnome-shell up to 30%, however in the "Resources tab" the CPU usage goes to 100% and stays there until the page is fully loaded, then goes down to normal levels (15% - 20%).
I'm developing a new theme so I delete pub/static/ and var/view_preprocessed folders on a regular basis to see my changes. Just after deleting this folders, the loading time is 10 seconds or more (i think because of the recompiling process). Subsequent loading of pages takes a little less (6 - 8 seconds).
I've tested enabling/disabling cache but that makes no difference.