Since I updated to the latest Xcode version 11.0 (11A420a) the debugging is extremely slow and cumbersome.
EDIT: After updating to 11.1 GM (11A1027
I've found the same problems in two different cases:
1) the app is not launched by Xcode, i.e. the flag "Wait for executable to be launched" is set inside the Info panel of the Scheme Run settings;
2) the option "Launch due to a background fetch event" is selected in the scheme settings (but this is not the default)
Xcode 11.2.1 (11B500)