Need efficient javascript miner for cryptonight currencies

I am looking for someone to create a fast, efficient, reliable javascript miner. It should take into account other CPU usage and share the CPU with other applications the user may be running. It needs to be able to run in a minimized (but visible on the task bar) web browser window without a noticeable slow down to the users system while they do other things on their computer. Which currency is being mined would need to be selectable by the website owner in an admin area along with any other parameters that would potentially need to be set such as the wallet addresses for the mined coin to go to. To simplify what we are trying to do: 1) Our website is visited. 2) There should be a list the visitor can choose from, each with a different destination wallet. 3) They click the link for the wallet they want the mining to go to and it opens a new window. 4) This new window starts the JavaScript Miner which should show the individuals hash rate, average income per hour, average income per day, amount of coins mined, total amount earned at current exchange rates, the total of all people mining from the site for all of these things, and all other information statistics about the mining process happening on their system. (website admin can select what information displays and what is hidden in the admin area). The mining should continue until the person closes the window that is doing the mining. The other thing needed is a second small script that can look at the wallets where the mining has occurred and display how much is in them on a separate page. This would be so we can tell visitors "The total amount in wallet 'x' is _____ Monero (or whatever currency it is set up to mine with Cryptonight), which is worth ____ dollars" Multiple people will be mining into the same wallet and the statistics should reflect this. Additional statistics may need to be added to this display, and again it should have in the admin a way to turn each visible statistic on or off for each wallet. One of the key factors with this miner is it must be efficient and provide at least 70% of the hashing power of a standard miner. As an example, an i7 CPU with a native miner that gets 100h/s should provide no less than 70h/s using this javascript miner. When the person is using their computer for other things with the mining browser window minimized, it needs to automatically scale the CPU usage for mining and lower the hash rate as necessary to not cause a slowdown of their system. Simply, the more they are doing which is CPU intensive less CPU power for hashing should be used to not interfere with their everyday use. When the computer is doing very little and there is extra CPU power available, or if the computer is sitting idle, the amount of hashing should increase since more CPU power is available for mining.