I work for an underground utility locating company in southeast Texas. Over time, the requirements of the job cause me to literally drive down every street in my area. Because of this fact, I use Wigle Wifi war-driving app and eventually will get mappings for every access point in my area.
Now for the question:
Wigle Wifi shows the wifi refresh rate at the top of the screen within the app. On stock KH7 and KK6, this rate shows 3500ms. In ICS, the user is allowed to select 2.4 GHz, 5 GHz, and Auto. Just scanning 2.4 GHz, the refresh rate is cut down to 1000ms, about 1/3 the rate that "Auto" does. In this mode, (depending on the rom I'm running at the time) the rate varies from a low of 900ms (on Shostock ICS 3.0.1 and PhoneBricker) to a high of about 1200ms (CM9, AOKP and Serendipity 9). It always scans at the same rate regardless of OC/UV. Some kernels that have references to wifi in their change logs or feature lists will enable the faster refresh rates on roms that didn't have it before (Fluxi is the only one that comes to mind at the moment, there may be more).
Can anyone tell me what causes the different scan rates between these roms? Wifi references in kernel/rom feature lists don't really point to a cause for the difference. I know that just 300ms difference might seem like I'm splitting hairs, but at near highway speeds, it really makes a big difference in the number of AP's I can catch.
Sorry for the long post. I know we need to keep them short and sweet, but I felt the research I've done so far needed to be included here.
Thanks to everyone who contributes to this community, especially the devs!