Best answer, in my opinion, is to not justify the text. Justified text looks pretty but is harder to read.

Is the text at the end of a line broken by a line break (shift-enter)? If so, Word will give huge breaks. If you simply press Enter at the end of that line it will improve matters.

Otherwise, you can set a compatibility option.
File > Options > Advanced > Compatibility Options
Click on layout options and check
"Do full justification the way WordPerfect 6.0 for Windows does"