Hi, sorry for not getting back earlier, just noticed now that you closed the other bug report.
I just installed 0.50-4, and the memory leak situation is still there and very noticeable. Starting it with -Xmx512m caps memory usage at about 717MB.
At gamebase selection screen: 75MB
After opening GB64 v08, and before doing anything else: 298MB
Moving to the next game with arrow down adds about from 0-10MB each time, could not establish relationship with number of screenshots or other.
So memory usage keeps increasing while moving down with arrow key until heap size limit is reached.
Unfortunately at that point the frontend becomes completely unusable, with message like the following in the console:
Exception in thread \"Image Fetcher 0\" java.lang.OutOfMemoryError: Java heap space
At this point I can still select games in the list, but no screenshots or other images are loaded.