You could be right on some of those. That didn't seem to be the prevailing attitude when I worked in that area, but as I said that was a long time ago - and it was in only a few specific sub-domains as well.
Forgot to mention: cache misses can be more expensive than uncached accesses, so testing with caches off and then turning them on in production can be a disaster if you hit a cache-busting access pattern. Always run what you tested.
