Make sure that when you're using a slotted screwdriver, you're not doing it the hard way. Here's how. Be sure you're using the right size screwdriver. The head should be approximately the width of the screw head. The tip should fit snugly into the slot of the screw. If it's narrower, you lose power. For more power, try a screwdriver with a larger handle. Pre-drilling pilot holes can save work, too.
For more on tools, consider:
The Essential Toolbox
How To: Use a Phillips-Head Screwdriver