Just in case you don't, let's walk through it again.
UCS-16 big-endian represenation of Ä:
0x00 0x41 0x03 0x08
Another UCS-16 big-endian representation of Ä:
0x00 0xc4
If you look at the number of bytes, the first example has 4. It represents one letter. The second example has 2. It also represents one letter. Conclusion: UCS2 does not "count unicode characters faster than UTF8." You still have to look at every byte to see how many letters you have, same as in UTF-8.
Do you grasp this? If not, maybe you are one of those "ascii-centric ignorant morons" I keep hearing so much about.