UPDATE 7/10/2014
I used to be a TESO gamer like you. Then I took a patch to the game client from Zenimax...

Consider this my official notice of resignation.
"Destiny Beta - Xbox One (Global) Come back on Jul 23 2014 to get your beta code!"

My .bat file will work as long as Windows has effectively the same cmd functionality.

I offered to turn it over to another party. No one wants it, and I won't be here to watch over it. But as said before, it shouldn't stop doing what it does.

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UPDATE: 6/25/2014
For those who have been brave and downloaded my insignificant and tiny file to help get just a little more from your game, I imagine by now most of you have updated the game client and gotten a chance to log back into the server. My .bat file does not use the Zenimax API or the LUA. It works at the OS level, elevating priority and limiting core access so as not to choke the system. Having said that, I myself have lost 20fps, and no amount of tweaking or changing settings will get it back. I can't create what has been taken away in the code. I don't know exactly what may have been changed in the game client. All I know is that I've personally seen a significant performance hit, and there's nothing I can do to fix or mitigate the issue.

I of course will look into it and see if there is any path to help restore what's been lost, but my skills are limited.

To those who've claimed this achieves nothing more than a "placebo" effect, I quote directly;
found at WHY DO I GET RANDOM 5-SECOND FREEZES? Updated 06/19/2014 11:35 AM - Published 04/19/2014 02:54 AM

I just discovered this today while posting to the Addons forums about all of the addons I use being broken, post patch. Note that Zenimax points out that doing as advised can slow other programs down. Those programs could include things like your video card drivers, sound card, and other important system resources - hence why my .bat limits the number of cores available to the game client.

I hope that my small contribution still helps to provide a better experience in game than you would otherwise achieve, assisting in making your time in Tamriel more enjoyable.

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First let me say I'm not a scripter or programmer. I was a UI wizard, meaning lots of exceptionally deep and esoteric photoshop secrets... that was almost a decade ago now. I have a small little something I would like for the developer community to play with. It'll help a game run a little better. At 32 bytes it's not a world changing thing, but it's just that little extra sumthin' sumthin'.

Here is a link to the FAQ.
Many of the things listed in the To Do list are covered in the FAQ, though certainly not all.

Now, if you've less or more than 8 logical cores you will need to discover how many logical cores your PC has and edit the file (most likely with Notepad). The "magic number" for an i7 Quad Core is 55. This is hex for 01010101. So, less or more cores, please choose a proper binary representation and convert it to an appropriate hex value and insert in place of "55". (0 means core off, 1 means core on).

Note: A "proper binary value" will be a single digit representing each logical core. For two cores ##, for three cores ###, for four #### and so forth. The idea is to allow about half of your cores to run the game client in an elevated priority. Since an i7 shows the OS it has eight logical processors, all of those cores on would be 11111111, all off would be 00000000. for an i7 half on could either be 10101010 or 01010101 - this string will be need to be converted to a hex value.

Place the start.bat file into your eso.exe dir. Double click to run, it'll launch the client.

Note: This bypasses the launcher. Any time there is an update you will need to run the launcher to download and install the update. Failing to do so will present you with a login screen that says Your Game Client Is Out Of Date. Please Run The Launcher To Update Your Game.

So, the point of the exercise? The game client can be a bit sluggish, so we up it's priority to give it more resources to help it run better. But, it'd be a real problem if it hogs all the processes, so we limit the number of cores it has elevated privileges on and allow other system functions and applications to have normal unrestricted access to system resources on the other cores. Pretty simple. Net result - it smooths things out a bit. And, that's about all it does.

I'd very much appreciate having some people who understand and can manage such things to give it a go, and if possible provide some constructive feedback.

Note: I don't provide support. (Even though in fact I have been...) There's several reasons for this. The main being that if you already don't know more about this than I do, it's unlikely I have the knowledge to offer much assistance. No, seriously. This is monkey butt simple. If it causes some type of problem, providing some type of explanation is out of my element. Like a fish out of water and in the vacuum of space kind of out of my element.

Please also understand this is not an "addon". It doesn't use LUA, it's not a UI component, or a .lib and really isn't even valid to list as a utility. It's a 32 byte .bat file that makes changes you can do manually in the Task Manager, but allows you to double click a single file to accomplish the same effect.

To Do List:
Finish the icon.
Create a more user friendly instruction set to post to page. (Read as step by step setup)
Add step by step setup illustrative images.
Add warning as to system requirements. (Windows XP and up)
Add warning as to other requirements. (Multi-core/Multiprocessor system only, valid account with Zenimax, operative game instal.)
Add warning as to "Enjoy using! Don't bother writing if it fails!" notice.
Add warning that using this will not run Zenimax's launcher, so any updates will not be downloaded and applied. To update the game to the latest version one must run the launcher. No changes to this file should be required, unless they rename the game client .exe file.
Add notice concerning fact that this single 32 byte text file is not, and will not change your system in ANY way, period.
Or your game settings. In any way at all, ever. (Read as: NOTHING IS EVER CHANGED IN ANY WAY)
Add notice that deleting said file(s) from computer utterly completely removes said files and any and all effects they ever possibly provided. As absolute and irrevocable as death and or taxes.

I thank you all for your time.