Hi Denis,
There are numerous reasons which could cause your app to slow down and it takes a lot of effort to find the root cause and sometimes even when you have found the root cause it's hard to solve. Having said that, I'm always intriged by solving performance problems.
The differences between localhost and a cloud environment:
So I would advise to first find out which calls are being made from client to server, I mostly use the Developer Tools (F12) > Network to check this.
And secondly inspect which database calls are being made. An strong indication is the warning log "Query executed in 10 seconds and 193 milliseconds". Do you have that? In that case: try to lower the number of access rules, as these are making the queries most complex.
Good luck!