Since some times (long time actually) I faced numerous lags during games preparation :
Lobbies listing refresh and sort (horde and escape)
Entering a lobby
Personalization (class and skins)
Ghost countdown before game
…
It made entering the game a pain. But I thought it was « standard » and as my network was not the root cause I let it like that until this we.
I decided to uninstall the game from my XBoxOne S and reinstall it again.
And miracle : no more lag, refreshing is almost instantaneous and personalization inside a public lobby is fine again. No more ghost countdown.
Installing the complete game with DLC took me nearly 12h but it was worthy.
Been having the types of issues you dscribe for a while too. On and off. Last night, fine! A couple of nights ago, lag on everything, outside of actually playing in a match.
I hope it will work for you. Note that in my case, the lags happened consistantly outside of any ping values or network low rate. And in-game there was no problem.