To easily unlock the "Star Performer" achievement, play San Francisco in Co-op mode. The cards and items in San Francisco are easier to find than in any other level. Collecting all cards and items in any level will unlock"Elite Agent" rank, which also unlocks the "Star Performer" achievement.
ACHIEVEMENT - HOW TO UNLOCK Finder's Keepers (20 points) - Find all 8 Items in a City Location in the Single-Player or Co-Op Mission. Quick on the Draw (10 points) - Find 3 items within 5 seconds. Bonus Plan (10 points) - Find all 9 Bonus Items in one Mission. Not Impossible (10 points) - Beat one Mission. The First Hint's Free... (10 points) - Beat one Mission without using any Hints. Just Said "No" (25 points) - Beat every Mission without using any Hints. Wham, Bam... (25 points) - Beat a City Location in less than 30 seconds. Star Performer (25 points) - Earn Elite Agent Rank in any Mission. You Always Remember Your First (10 points) - Beat Mission 3 and capture Mister Smith. Back for Seconds (15 points) - Beat Mission 6 and capture The Hammer. Third Time's the Charm (15 points) - Beat Mission 9 and capture The Artiste. Fourth Down (25 points) - Beat Mission 11 and capture Dr. Chaos.