Methods and devices are disclosed for enabling improved efficiency and performance in idle mode processes on a multi-SIM wireless communication device currently operating in single SIM or multiple SIM multiple standby mode. After determining that the first SIM and/or second SIM are using the first RF resource and the second RF resource is unavailable, the wireless device may determine whether the first RF resource is operating in idle mode. Upon determining that the first RF resource is in idle mode, the wireless device may identify at least one idle-mode task to be performed by the first RF resource, identify parallelism parameters, identify possible parallelism task combination sets based on the at least one identified idle-mode task and the parallelism parameters, select a best parallelism task combination set, and assign parallel tasks to the first and second RF resources according to the selected parallelism task combination set.