it depends on what type of card you get and what do you stuff it with

if you get those slow a$$ cards like the one im having (Adata 2GB miniSD) it'll lag.but its not too bad.just lag at certain areas like gallery

and if you stuff ur card up to like 90%+ then you'll definately notice a slow down in speed.since it takes time to read all those data that you have in ur card.

Go for those high speed models.its around rm100+ for a 2GB stick

such examples are Transcend 80x miniSD,Apacer 120x miniSD and Twinmos.