Are you sailing with the windward telltales lifting on the jib, or are both sets (windward and leeward) streaming aft?
If you are sailing with the windward telltales streaming aft, you are footing off, which is fast but dont usually give best VMG. Windward telltales should lift 15-30deg when in pointing mode (which is after the start when you have free wind).

How old and how much use have your jib seen?