To ride a berm fast, you have to pick your line correctly. Beginning your turn wide means you are able to ‘cut’ across the berm towards your exit line, with minimal braking, as the bike will find a natural arch throughout the berm. If you enter the berm too low, you’re at risk of being too far up the berm before you’ve finished turning causing you to brake.
To ensure you ride through the berm in one smooth motion, keep your head up and look down the trail to your exit routes. This will ensure you stay adaptive to the cycle trail conditions and can react to any obstructions or changes ahead.