If you looking for a fast low pin count interface to an LCD (can't be lower than a single pin),
you might be interested in this recent activity:
https://bitbucket.org/fmalpartida/new-liquidcrystal/pull-request/1/adding-an-optimized-implementation-of/diff#comment-366944
Although the interface uses a single pin, it can transfer bytes in 92us for a frame rate close to 320 FPS,
which is about 3.6 times faster than the standard LiquidCrystal library using 6 pins!
This is a great example of how inefficient the Arduino core routines like digitalWrite() are.
It is about 6 times faster than the optimized i2c i/o expander interface.
While more components and a bit more complex than using something like a PCF8574 i/o expander chip,
the total component cost should be lower given
595s can be had for about (USD) 20cents and transistors are about 2-3 cents
and caps and resistors are about 1 cent - all quantity 1 from places like tayda.
--- bill