A method and system pre-emptively perform garbage collection operations of a forced amount on update blocks in a memory device. The amount of garbage collection needed by a certain data write is monitored and adjusted to match the forced amount if necessary. Update blocks may be selected on the basis of their recent usage or the amount of garbage collection required. Another method and system may store control information about update blocks in a temporary storage area so that a greater number of update blocks are utilized. The sequential write performance measured by the Speed Class test may be optimized by using this method and system.