nrf52832 scan channel switch time

Question

I use nrf52832 + SoftDevices132_nrf52_3.1.0. 
 sd_ble_gap_scan_start() run with scan_interval=scan_window=5ms. 
 I look at scan-channel-switch time is about 1ms. (I analyze current consumption.)
It's so many. 
 I want reduce switch time. 
 Add,
I programed. 
 static const ble_gap_scan_params_t scan_params = {
.active = 0,
.use_whitelist = 0,
.adv_dir_report = 0,
.interval = 0x0008, /* 5ms /
.window = 0x0008, / 5ms */
.timeout = 0,
};
...
...
uint32_t err_code = sd_ble_gap_scan_start(&scan_params);

bjorn-spockeli · Accepted Answer

It is correct that the nRF52832 is able to switch channel frequency much faster, as fast as 40us, see the Radio Timing section in the nRF52832 Product Specification. 
 However, the SoftDevice will reserve at least 760us after each
each ScanWindow, refered to as tScanReserved in the S132 SoftDevice Specification. So the behaviour you're seeing is to be expected.