It's recommended to use a max. resolution of 1024x768 pixels.
Generally each background picture uses GUI memory, dependend only on the resolution. If enough physical memory is provided by operating system the amount of GUI memory can be changed in the file:
<Industrial HiVision Installation Folder>\config\HiVision.emv
This file can be edited. The memory is configured by the parameter USEMAXMEMJVM. The default value is 384 MB. Please change the line
set USEMAXMEMJVM 384m
set USEMAXMEMJVM 512m
in order to reserve 512 MB.