I am assuming you are programming Favorites and not using the zip code method. Furthermore, I am assuming you are not listening the the full DB. I don't use search with scan.
My SDS 100 used to skip over talk groups and miss them on occasion. It was slow as a snail on Librium. My 436HP was hitting on most.
So, I made some adjustments.
In the profile, I made sure that the "use site NAC" was checked. This works quite well in a statewide system. Instead of the radio search for the NAC site code, it hits like a charm.
In the Favorite, I make sure that the hold time is set to 0.
Then, I set the delay at the talk group level to 4 seconds.
I made sure I group my favorites in to "startup configuration keys."
I 'stack" my conventional and talk groups. Most of the time, I stack my talk groups instead of leaving them under all of the various departments. I put the sites I am monitoring within the Favorite and stack all of the talk groups beneath these.
I might add, I make sure my conventional frequencies list is as few as possible. I believe conventional frequencies slow this radio down.
Also, in the profile, I set the "global auto filter" to normal.