A system and method for improving storage system performance by reducing or avoiding load spike amplification when performing garbage collection is disclosed. A storage controller in a storage system tracks system load including write load and read load, as well as available free segments. The storage controller uses these tracked values as inputs and, with these inputs, generates a garbage collection rate. Where read load is included, a scaled portion of the read load is taken into consideration so that, as the number of free segments nears the minimum amount desired and to prevent garbage collecting too slowly, the read load is gradually excluded from the garbage collection rate determination. The garbage collection rate is therefore responsive to system load so that, in times of high system load, the rate reduces as much as is safe so that the write load takes priority with computing resources of the storage controller.