Just released GSview 4.41 beta. This fixes two stupid bugs with the X11 version.
First I assumed that everyone would have the LANG environment variable set (wrong). It worked on my system but crashed on start-up on others.
Secondly my code for progressively updating the display during rendering on X11 queued up a whole series of screen updates when displaying on a slow X11 server. The code then sent these updates one at a time to the remote X11 server. This is very slow on a remote X11 server (tens of seconds), but hardly noticeable on my local display used for development. Having an old X server on a 10M Ethernet is recommended for testing. What now happens is that when it finds a screen update in the queue, it looks at what else is in the queue and merges them as appropriate, minimising the number of updates sent to the X11 server. This is obvious in hindsight (I already knew that Windows does this with WM_PAINT), but when you are doing this on a new platform for the first time you can't see the wood for the trees.