Compare:
image viewer (Windows 7 64-bit | 4 Core CPU | 10 GB RAM) Superfast 0,5 - 1 second NOT FROZEN
IrfanView 4.38 32-bit - 5 second + temporary high CPU load + temporary frozen Windows
XnView MP - 3 .. 5 second + temp. frozen
XnView STANDARD - 1 second OPEN but a little slow(1-2 second) closing program
I installed XnView MP and very disappointed - very slow in opening images

How to improve the speed? Second in the opening are very, very, very important for me!