It may still make sense to increase the default batch size -b 1024 to something like -b 4096 or -b 8192 when running interactive mode with scrypt-jane. This costs a bit of display smoothness, but adds more hash/s.
Thanks for the tip ! - increased my 770M hashrate from 1.1 to 1.33 on windoze (-b 4096)
Using -b 8192 I was able to increase my hashrate from 1.11 to 1.26 on my GTX 650. Doubling to 16384 didn't seem to have an effect.