I am testing BLE Peripheral as a beacon, transmitting at 100 ms latency and it is working great.
https://www.b4x.com/android/forum/threads/ble-peripheral.84051/#content
My receiving tablet with Android 7.0 is using a modified Erel example - BLE2 (Ble Central) to scan for the peripheral beacon's UUID and is working great (just want to find, not connect).
manager.Scan2(Array(ServiceId),True)
I tried the same app with a tablet using Android 8.0 (Samsung Tab S4) and there is a significant delay in Device_found.
(Yes I tried the same code with target 26 and run-time permissions, it did not make a difference).
The pic shows the speed difference between Android 7 and Android 8.
(I tried uploading my Ble Central app .zip, but posting said file too large - 603 kb)