One trick I found to speeding up SDS or HP scanning, at least for trunking, is to ENSURE that you have the active or default control channel at the TOP of the control channel list when programming. If you watch an SDS or HP scan across a trunked favorites list, you will see it scan down the control channel frequencies on the display until it finds the control channel and starts receiving. If you put the active at the #1 spot, you will see as it scans across and back to that system/site, it will display the control channel right away and there is no delay in it beginning to decode and receive talkgroup traffic.
Paul