SharePoint 2019 is very slow

Good afternoon,

I am about to migrate my SharePoint sites from 2016 to 2019.

I just finished configuring my SharePoint 2019 server, but it is much slower than 2016.

This problem could be my fault: I decided to divide my 4 secondary sites into 4 sites. So, instead of having:
http: //sps16/sites/company1/default.aspx
http: //sps16/sites/company2/default.aspx
http: //sps16/sites/company3/default.aspx
http: //sps16/sites/company4/default.aspx

Now I have:
http: // sps19: 3000 / default.aspx
http: // sps19: 3010 / default.aspx
http: // sps19: 3020 / default.aspx
http: // sps19: 3030 / default.aspx
So, 4 web applications instead of 1.

Is the problem?
At this time it is not usable, since it is very slow (and I have not yet started the migration).

Thank you

Christophe