[p1esk]

4x seq length expansion doesn’t sound that bad.

[lechatonnoir]

I mean, it's not completely fatal, but it means an approximately 16x increase in runtime cost, if I'm not mistaken. That's probably not worth trying to solve letter counting in most applications.

[SEGyges]

it is not necessarily 16x if you, e.g., decrease model width by a factor of 4 or so also, but yeah naively the RAM and FLOPs scale up by n^2