It occurred to me that Steven M. Bellovin wrote in gmane.os.netbsd.general:
>>So, yes, lpa is very tied to the parrallel port device, and you really
>>shouldn't use it to begin with, if you can avoid doing so.  You really don't
>>want a polled driver if you can afford an interrupt driven one.
>>
> My experience is just the opposite -- I found that polling drivers 
> worked much better.

I'll admit immediately that I haven't done a *lot* of testing, but I noticed
that my trusty old LaserJet wasn't printing any faster while using lpa
when compared to lpt. That's probably because my laserjet isn't setting
any landmark records.

However, what I *did* notice was that the lpa driver was taking a
generous amount of resources in comparison to the lpt one.