I'm just wondering why I get such a high score on this site, but when I do a typing test at an employment center, I get a considerably lower score.

My tip to improve your typing speed is to keep practicing. There is no substitution for practice. Also, learn not to think about the words you are typing. If you do so, then you get distracted and make mistakes.

When my fingers hurt after too much time on the keyboard, I take a break.