Write to Cartridge RAM less frequently

[joeldipops]

~~Occurring in Donkey Kong Land 2. Once you're in a level, every few seconds the display will freeze for 500 - 1000ms.~~

~~I thought this might have been the flush to cartridge, but I commented that out and had the same behaviour (unless the flash cart is doing weird stuff and running the wrong file again.)~~

~~At any rate, the flush to cartridge probably can be less often than once a frame, I imagine it will cause slow-down somewhere.~~

Tried again with an obviously different file and the jankiness cleared up, so I think writing to the cartridge is probably the culprit after all