With your current configuration, do you see your memory usage going up and have the screen slow down if you switch between this screen and another or refresh this screen frequently.
I had a project that had a rather complicated set of templates that I displayed using a Template Canvas and I ended up reducing the size of the list from the 20 the client requested down to 10 because when switching to this window eventually the client froze because it ran out of memory. My forum post
Note that one of the things I had to do was adjust memory allocation to the JVM. If you haven't done that you might wish to investigate appropriate values for the JVM heap.