Which android version are you running?
Settings >>> About phone (if I remember correctly)
And you can do something about the lag. (Installing a diffferent home is always a good start but for next instructions the version is needed) Dunno what you mean with text :P (am not english) but if its the messaging app from htc, use some alternative like handcent from the market. If its the keyboard, try again some alternative

(better keyboard, swift key, swype etc)