It is beyond my knowledge, I was trying to make NTSC version but looks like there was not enogh cpu cycles per frame, maybe it could be done using timers insted of raster synchronization - I am not sure - but such approach would require a lot of changes.
I don't know why but on WinUAE 5.3.1 the game gets guru in most cases when running from hd. I was using WinUAE 4.3.0 during development and the game runs on this version without any problems.
In most cases when pepole report such kind of problem it is caused by missing "assign" call (I will try to change it), before running the game (from HD) try to execute in CLI: assign Yoomp!: path_to_install_folder where path_to_install_folder should be full path with hd drive name
I don't know why but I had problems with latest WinUAE 5310, I'am not sure why. Maybe it's case of reconfiguration while it running (I am avoiding to do such thing now), anyway sometimes when i run WinUAE it works ok but in some occasion after loading WB my every try to run the game ends with guru.
Did you check latest version 1.01? It makes sense to load whole data into memory when it is available but my primary goal was to make it work on system with smaller amount of memory. I will think how much changes it will take to load and use all game data from memory.