Possible bug with bindkey and Unicode characters in 5.2?

["Raymond W. Ko" <raymond.w.ko@xxxxxxxxx>]

Hello, I am using Arch Linux, and zsh 5.2 recently landed in stable. I 
then discovered that some of my bindkeys with Unicode characters broke. 
I am basically using http://oremacs.com/2015/02/14/semi-xmodmap/ to 
generate unicode characters, but that should not be relevant.

Here is the relevant part of my .zshrc:

bindkey -s θ '"\C-b"'
bindkey -s ω "'\C-b'"
bindkey -s υ ">\C-b<"
bindkey -s σ "}\C-b{"
bindkey -s φ ")\C-b("
bindkey -s φ "asdf"
bindkey -s ρ "]\C-b["

On zsh 5.1 and 5.0.1, this works as expected. However, in 5.2 there 
seems to be a pause for half a second before a question mark appears. I 
have tested this on mintty, xterm and urxvt, and Linux and Cygwin, so I 
don't think this is terminal specific. Any ideas? Downgrading back to 
5.1 works for now.