i want the best speed operating system.
More bits doesn't mean more speed. In fact, Unless you have a CPU that can process 128 bit commands, your programs are likely to run slower, because you have to split up the 128 bit operations back down to 64 bits, and then combine the results back to 128 bit. That doesn't really make a lot of sense, because you keep all the drawbacks of 64 bits plus the conversion overhead!
If you can get a 128 bit CPU. the conversion oberhead will of course vanish. But that still doesn't mean your programs get faster. The only case where this would cause a speed-up is operations on integral numbers greater than 2^64 or floating point numbers with a precision of more than 15 decimal digits.
However, with a 128 bit CPU you will need more memory because you'll want your data aligned at 128 bits instead of 64 bits, to make the laod and store operations more efficient. This means you'll likely need padding bits if you want to maintain the best possible speed.
I've heard of a 128 bit CPU back in the 90s, but apparently there are too few applications that could take advantage of this that there is no interest for mass production. Consequently, even if these babies are actually sold to the public, expect to spend and arm ans a leg to obtain one.
tl;dr: Most probably this is neither what you want nor what you could afford. If you still think otherwise, maybe you should point out what it is you want to achieve - there may be other ways.