50x50 isn’t big at all and should not cause problems. Are you sure you’re rendering the map in a performant way? For example, are you perhaps rendering each tile with its own draw call, instead of batching them into fewer draw calls? Are you perhaps generating the drawable object(s) from the data on every frame, instead of having your drawable(s) created once and reusing it?
(This is very off-topic for this forum though, so I’d recommend taking it to DMs or another forum, as this one doesn’t have an off-topic section.)