300% is too much of a performance increase to assign completely to the write cache being enabled, although it does make a significant difference.  When the battery goes bad, the controller turns off write caching, and that is the source of the performance difference.  Unless you have a good and specific reason for disabling the cache (and I can't think of any good reasons), it should be enabled.  You can't force the controller to use the cache without the battery, besides it's dangerous to your data to use cache without a battery.

"Bottom line is that I am aiming for the highest performance for read and writes, thank you all!"

Bottom line ... enable write cache (write back) and replace batteries when needed (which should not be often).

Like I said, you should always enable Adaptive Read Ahead/Write Back, unless you have a good reason too (and, again, I can't think of a single good reason you'd need/want to).