Hi!
Just wanted to report that on my end, during a battle, it seems like any inputs temporarily freeze the renderer or game loop on both low-end and high-end setups, making gameplay somewhat tideous. Running the wheezy build of VCMI 0.90 on Linux Mint Debian, kernel 3.2. Data files come from Heroes 3 Complete along with Era 2.4.
Are there ways of mitigating the problem without the need to recompile the whole engine? Not that I could, since attempts to build VCMI_lib from trunk flip me off with an unsupported platform message. 
Hopefully I’ve provided enough data to narrow down the issue, but if not - ask.
Cheers,
zer0def