When composing documents in OS X, sometimes moving the cursor around with arrow keys is more convenient, and a bit more accurate, than using the mouse.
The arrow keys therefore offer a great advantage both in offering a precise input option (one tap moves over one character, or up one line, etc.), but also in that they are right there on the keyboard. However, if you are unfamiliar with the modifiers you can use with the arrow keys to place your cursor faster, you may resort to pressing and holding them to get the cursor where you want it.
Recently MacFixIt reader Bob wrote in with such a frustration:
How, sir, can I speed up my cursor when backspacing or advancing through text? It's maddeningly slow. Not so on my Windows machine. I've searched Google a dozen times. Even went to the local Apple Store. No ideas.
One thing you can do is change the Key Repeat setting in the Keyboard system preferences. The Key Repeat setting changes the speed at which inputs are accepted if you hold the keys down, so if you set it to a faster rate, the cursor will move faster when you hold a key down. I recommend that most people use its fastest setting. You can also adjust the Delay Until Repeat setting to change the time you must wait after initially pressing and holding the key for the system to accept repeated inputs.
However, even with these options set, some people may find the arrow keys to still be somewhat slow for placing the mouse cursor where they would like, especially for larger bodies of text. If you would like to place the cursor around your document far quicker, you can use modifier keys in conjunction with the arrow keys.
By holding the Option key when pressing the left and right arrow keys, you will advance the cursor on a per-word basis; if you hold the Command key instead, you will jump to the beginning or end of the current line.
For the up and down arrows, if you hold the Option key, the cursor will jump to the beginning or end of the current paragraph; the Command key will alter this to jump to the beginning or end of the current document.
You can combine these shortcuts with the Shift key to expand or contract a highlighted selection of text. For example, if you would like to select from the current cursor location to the beginning of the paragraph, then press Shift-Option-up arrow, or if you would like to select only the last typed word, then press Shift-Option-left arrow.
You can also use the mouse to select some text, and then use these key combinations to refine the selection. If you do this, keep in mind that the part of the selection that is modified will be where you released the mouse cursor when making your selection, regardless of whether it is before or after the initial point of your selection.
This should help you make quick work of text navigation, and vastly increase the speed at which you edit documents.