Many things come to mind when I see this problem. Is the engine running at top speed? Should be approximately 3400 RPMs. Are you cutting at a correct height? Should be removing no more than 1/3 of the grass height, on dry grass. Is the blade turning at top speed? Worn or loose belt will slip, allowing the blade to turn slower. Are you using a blade for bagging? High lift blades are the best. Finally, I’ve found that the 30” TroyBilt mowers are on the low end of good bagging systems.