I've used a BT keyboard for years and am the fastest typist out of every developer I've met so clearly something is wrong with your statement.
* Apple Wireless Keyboard
* Logitech K 300
* Microsoft -god-knows-what-it-was-called- from back in the day.
In all cases, I experienced stuttering or dropouts of my input at high speeds. This did not happen all the time, but it was frequent enough where I felt the need to go back to a wired keyboard (currently Filco Majestouch). Maybe I had a bad batch, or something was interfering with the signals in my homes. Either way, I don't plan on recommending wireless alternatives for quite some time.
Not that I'm seriously suggesting it, but it occurs to me that you should be able to make something with an Arduino to make any kb bluetooth.