Yes you can and it's so obvious that it's possible you might be doing it already - hold A. Just to be certain, I started up my copy and tested several combinations of input to come up with this answer. According to the game manual's control section (page 12 in my copy), it says:
Confirm selections/advance on-screen messages.
This doesn't overtly answer your question as text dialogs ask you to press A to advance to the next screen of text, in fitting with what the manual describes. However, it should be noted that holding A while text fills the dialog makes the text fill the dialog somewhat faster and this can also be considered advancing on-screen messages. The increase in text speed offered by holding A is not dramatically significant so you may not notice it at first, but to verify that there is a difference, all you need to do is let a dialog fill with text without holding A and it should be clear. Even holding A part way through a dialog filling with text is a sufficient demonstration of the difference.
On the same page of the manual, it also says:
- During a conversation, hold down the R button and A button simultaneously to have the conversation automatically advance.
As noted in the manual R + A skips over text dialogs, often before the text is even near finished being printed to the screen as you have noted.
To have speed and control of a text dialog, all you need to do is hold A all the time in text dialogs, and when you've finished reading the current screen of text, tap (but do not hold) R to advance the dialog to the next screen.